sanitizing NULLable config values

10 files changed, 182 insertions, 249 deletions

diff --git a/pdf-over-commons/src/main/java/at/asit/pdfover/commons/Messages.java b/pdf-over-commons/src/main/java/at/asit/pdfover/commons/Messages.java
index 6ed52d5b..04c8583a 100644
--- a/pdf-over-commons/src/main/java/at/asit/pdfover/commons/Messages.java
+++ b/pdf-over-commons/src/main/java/at/asit/pdfover/commons/Messages.java
@@ -22,6 +22,8 @@ import java.util.Locale;
 import java.util.MissingResourceException;
 import java.util.ResourceBundle;
 
+import javax.annotation.Nonnull;
+
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
@@ -49,13 +51,13 @@ public class Messages {
 	 * Get the closest match to the system default Locale out of the supported locales
 	 * @return the default locale
 	 */
-	public static Locale getDefaultLocale() {
+	public static @Nonnull Locale getDefaultLocale() {
 		Locale ld = Locale.getDefault();
 		for (Locale l : Constants.SUPPORTED_LOCALES) {
 			if (l.equals(ld) || l.getLanguage().equals(ld.getLanguage()))
 				return l;
 		}
-		return Constants.SUPPORTED_LOCALES[0];
+		return Constants.ISNOTNULL(Constants.SUPPORTED_LOCALES[0]);
 	}
 
 	/**
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/MainWindow.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/MainWindow.java
index 79600265..2ce60634 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/MainWindow.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/MainWindow.java
@@ -229,7 +229,7 @@ public class MainWindow {
 			@Override
 			public void shellClosed(ShellEvent e) {
 				log.debug("Closing main window");
-				MainWindow.this.stateMachine.configProvider.setMainWindowSizePersistent(getShell().getSize());
+				MainWindow.this.stateMachine.configProvider.setMainWindowSizePersistent(Constants.ISNOTNULL(getShell().getSize()));
 				try {
 					MainWindow.this.stateMachine.configProvider.saveToDisk();
 				} catch (IOException e1) {
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/bku/MobileBKUConnector.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/bku/MobileBKUConnector.java
index 78943eee..995cc537 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/bku/MobileBKUConnector.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/bku/MobileBKUConnector.java
@@ -103,7 +103,7 @@ public class MobileBKUConnector implements BkuSlConnector {
         }
         lastHTTPRequestTime = now;
 
-        log.debug("Sending request to '{}'...", request.getUri().toString());
+        log.debug("Sending {} request to '{}'...", request.getMethod(), request.getUri().toString());
         try (final CloseableHttpResponse response = httpClient.execute(request)) {
             int httpStatus = response.getCode();
             if ((httpStatus == HttpStatus.SC_MOVED_PERMANENTLY) || (httpStatus == HttpStatus.SC_MOVED_TEMPORARILY)) {
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/configuration/AdvancedConfigurationComposite.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/configuration/AdvancedConfigurationComposite.java
index 20c8fdfd..d9ea02ed 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/configuration/AdvancedConfigurationComposite.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/configuration/AdvancedConfigurationComposite.java
@@ -22,6 +22,8 @@ import java.util.List;
 import java.util.Locale;
 import java.util.stream.Collectors;
 
+import javax.annotation.Nonnull;
+
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.FocusAdapter;
 import org.eclipse.swt.events.FocusEvent;
@@ -246,7 +248,9 @@ public class AdvancedConfigurationComposite extends ConfigurationCompositeBase {
 		this.txtSaveFilePostFix.addFocusListener(new FocusAdapter() {
 			@Override
 			public void focusLost(FocusEvent e) {
-				performPostFixChanged(txtSaveFilePostFix.getText());
+				if (txtSaveFilePostFix.getText().trim().isEmpty())
+					txtSaveFilePostFix.setText(Constants.DEFAULT_POSTFIX);
+				performPostFixChanged(Constants.ISNOTNULL(txtSaveFilePostFix.getText()));
 			}
 		});
 
@@ -330,7 +334,7 @@ public class AdvancedConfigurationComposite extends ConfigurationCompositeBase {
 		reloadResources();
 	}
 
-	private void performPostFixChanged(String postfix) {
+	private void performPostFixChanged(@Nonnull String postfix) {
 
 		log.debug("Save file postfix changed to : {}", postfix);
 		this.configurationContainer.saveFilePostFix = postfix;
@@ -355,7 +359,7 @@ public class AdvancedConfigurationComposite extends ConfigurationCompositeBase {
 		return i;
 	}
 
-	void performBKUSelectionChanged(BKUs selected) {
+	void performBKUSelectionChanged(@Nonnull BKUs selected) {
 		log.debug("Selected BKU: {}", selected);
 		this.configurationContainer.defaultBKU = selected;
 		this.cmbBKUAuswahl.select(this.getBKUElementIndex(selected));
@@ -372,13 +376,13 @@ public class AdvancedConfigurationComposite extends ConfigurationCompositeBase {
 		}
 	}
 
-	BKUs resolveBKU(String localizedBKU) {
+	@Nonnull BKUs resolveBKU(String localizedBKU) {
 		int blen = BKUs.values().length;
 
 		for (int i = 0; i < blen; i++) {
 			String lookup = "BKU." + BKUs.values()[i].toString();
 			if (Messages.getString(lookup).equals(localizedBKU)) {
-				return BKUs.values()[i];
+				return Constants.ISNOTNULL(BKUs.values()[i]);
 			}
 		}
 
@@ -550,12 +554,7 @@ public class AdvancedConfigurationComposite extends ConfigurationCompositeBase {
 		if (outputFolder != null) {
 			performOutputFolderChanged(outputFolder);
 		}
-		String postFix = this.configurationContainer.saveFilePostFix;
-		if (postFix != null) {
-			performPostFixChanged(postFix);
-		} else {
-			performPostFixChanged(Constants.DEFAULT_POSTFIX);
-		}
+		performPostFixChanged(this.configurationContainer.saveFilePostFix);
 		performPositionSelection(this.configurationContainer.autoPositionSignature);
 		performUseMarkerSelection(this.configurationContainer.getUseMarker());
 		performUseSignatureFieldsSelection(this.configurationContainer.getUseSignatureFields());
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/mobilebku/MobileBKUEnterTANComposite.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/mobilebku/MobileBKUEnterTANComposite.java
index 28aaf4c7..dfd9dc40 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/mobilebku/MobileBKUEnterTANComposite.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/composites/mobilebku/MobileBKUEnterTANComposite.java
@@ -19,14 +19,8 @@ package at.asit.pdfover.gui.composites.mobilebku;
 import java.net.URI;
 
 import org.eclipse.swt.SWT;
-import org.eclipse.swt.events.ModifyEvent;
-import org.eclipse.swt.events.ModifyListener;
 import org.eclipse.swt.events.PaintEvent;
 import org.eclipse.swt.events.PaintListener;
-import org.eclipse.swt.events.SelectionAdapter;
-import org.eclipse.swt.events.SelectionEvent;
-import org.eclipse.swt.events.TraverseEvent;
-import org.eclipse.swt.events.TraverseListener;
 import org.eclipse.swt.graphics.Image;
 import org.eclipse.swt.graphics.ImageData;
 import org.eclipse.swt.graphics.Rectangle;
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/utils/LocaleSerializer.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/utils/LocaleSerializer.java
index 18d6e8c1..5d90ae6f 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/utils/LocaleSerializer.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/utils/LocaleSerializer.java
@@ -18,6 +18,10 @@ package at.asit.pdfover.gui.utils;
 // Imports
 import java.util.Locale;
 
+import javax.annotation.Nonnull;
+
+import at.asit.pdfover.commons.Constants;
+
 /**
  *
  */
@@ -49,7 +53,7 @@ public class LocaleSerializer {
 	 * @param locale the locale
 	 * @return the parsable string
 	 */
-	public static String getParsableString(Locale locale) {
-		return locale.toString();
+	public static @Nonnull String getParsableString(Locale locale) {
+		return Constants.ISNOTNULL(locale.toString());
 	}
 }
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/config/ConfigurationDataInMemory.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/config/ConfigurationDataInMemory.java
index 75fe5f89..e89f0924 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/config/ConfigurationDataInMemory.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/config/ConfigurationDataInMemory.java
@@ -19,6 +19,10 @@ package at.asit.pdfover.gui.workflow.config;
 import java.io.File;
 import java.io.FileNotFoundException;
 import java.util.Locale;
+import java.util.Objects;
+
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
 
 import at.asit.pdfover.commons.Profile;
 import org.eclipse.swt.graphics.Image;
@@ -34,6 +38,8 @@ import at.asit.pdfover.gui.bku.OLDmobile.MobileBKUHelper;
 import at.asit.pdfover.gui.exceptions.InvalidEmblemFile;
 import at.asit.pdfover.gui.exceptions.InvalidPortException;
 
+import static at.asit.pdfover.commons.Constants.ISNOTNULL;
+
 /**
  * Implementation of the configuration container
  */
@@ -74,8 +80,8 @@ public class ConfigurationDataInMemory {
 	}
 
 	/** The mobile phone number */
-	protected String mobileNumber = null;
-	public String getMobileNumber() { return this.mobileNumber; }
+	protected @CheckForNull String mobileNumber = null;
+	public @CheckForNull String getMobileNumber() { return this.mobileNumber; }
 	public void setMobileNumber(String number) {
 		if(number == null || number.trim().isEmpty()) {
 			this.mobileNumber = null;
@@ -85,12 +91,12 @@ public class ConfigurationDataInMemory {
 	}
 
 	/** The mobile phone password */
-	public String mobilePassword = null;
+	public @CheckForNull String mobilePassword = null;
 
 	public boolean rememberPassword = false;
 
 	/** Holds the proxy host */
-	public String proxyHost = null;
+	public @CheckForNull String proxyHost = null;
 
 	/** Holds the proxy port number */
 	protected int proxyPort = -1;
@@ -108,25 +114,25 @@ public class ConfigurationDataInMemory {
 	}
 
 	/** Holds the proxy username */
-	public String proxyUser = null;
+	public @CheckForNull String proxyUser = null;
 
 	/** Holds the proxy password */
-	public String proxyPass = null;
+	public @CheckForNull String proxyPass = null;
 
 	/** Holds the default BKU to use */
-	public BKUs defaultBKU = BKUs.NONE;
+	public @Nonnull BKUs defaultBKU = BKUs.NONE;
 
 	/** Holds the output folder */
-	public String outputFolder = null;
+	public @CheckForNull String outputFolder = null;
 
 	/** Holds the signatureNote */
-	public String signatureNote = null;
+	public @CheckForNull String signatureNote = null;
 
 	/** Holds the locale */
-	public Locale interfaceLocale = null;
+	public @CheckForNull Locale interfaceLocale = null;
 	
 	/** Holds the signature locale */
-	public Locale signatureLocale = null;
+	public @CheckForNull Locale signatureLocale = null;
 
 	/** Holds the PDF/A compatibility setting */
 	public boolean signaturePDFACompat = false;
@@ -136,13 +142,13 @@ public class ConfigurationDataInMemory {
 
 	/** Keystore signing options */
 	public enum KeyStorePassStorageType { MEMORY, DISK };
-	public Boolean keystoreEnabled = null;
-	public String keystoreFile = null;
-	public String keystoreType = null;
-	public String keystoreAlias = null;
-	public KeyStorePassStorageType keystorePassStorageType = null;
-	public String keystoreStorePass = null;
-	public String keystoreKeyPass = null;
+	public @CheckForNull Boolean keystoreEnabled = null;
+	public @CheckForNull String keystoreFile = null;
+	public @CheckForNull String keystoreType = null;
+	public @CheckForNull String keystoreAlias = null;
+	public @CheckForNull KeyStorePassStorageType keystorePassStorageType = null;
+	public @CheckForNull String keystoreStorePass = null;
+	public @CheckForNull String keystoreKeyPass = null;
 
 	/** Whether to automatically check for updates */
 	public boolean updateCheck = true;
@@ -151,7 +157,7 @@ public class ConfigurationDataInMemory {
 	 * 
 	 * @IMPORTANT this must always be valid and non-null, even if configuration failed to load for whatever reason (it is used by error handlers!)
 	*/
-	public Point mainWindowSize = new Point(Constants.DEFAULT_MAINWINDOW_WIDTH, Constants.DEFAULT_MAINWINDOW_HEIGHT);
+	public @Nonnull Point mainWindowSize = new Point(Constants.DEFAULT_MAINWINDOW_WIDTH, Constants.DEFAULT_MAINWINDOW_HEIGHT);
 
 	/** Whether to skip the output state */
 	public boolean skipFinish = false;
@@ -176,14 +182,12 @@ public class ConfigurationDataInMemory {
 	public boolean enabledPlaceholderUsage = false;
 
 	/**	The Signature Profile */
-	protected Profile signatureProfile = null;
-	public Profile getSignatureProfile() {
-		if (this.signatureProfile == null)
-			return Profile.SIGNATURBLOCK_SMALL;
-		return this.signatureProfile;
+	protected @CheckForNull Profile signatureProfile = null;
+	public @Nonnull Profile getSignatureProfile() {
+		return ISNOTNULL(Objects.requireNonNullElse(this.signatureProfile, Profile.SIGNATURBLOCK_SMALL));
 	}
 	public void setSignatureProfile(Profile profile) { this.signatureProfile = profile; }
 
-	public String saveFilePostFix = "_signed";
+	public @Nonnull String saveFilePostFix = Constants.DEFAULT_POSTFIX;
 
 }
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/config/ConfigurationManager.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/config/ConfigurationManager.java
index 37a44e71..95d3876b 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/config/ConfigurationManager.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/config/ConfigurationManager.java
@@ -23,6 +23,9 @@ import java.io.IOException;
 import java.util.Locale;
 import java.util.Properties;
 
+import javax.annotation.CheckForNull;
+import javax.annotation.Nonnull;
+
 import at.asit.pdfover.commons.Profile;
 
 import org.apache.commons.io.FileUtils;
@@ -39,6 +42,8 @@ import at.asit.pdfover.gui.utils.LocaleSerializer;
 import at.asit.pdfover.gui.workflow.config.ConfigurationDataInMemory.KeyStorePassStorageType;
 import at.asit.pdfover.commons.Messages;
 
+import static at.asit.pdfover.commons.Constants.ISNOTNULL;
+
 /**
  * Implementation of the configuration provider and manipulator
  */
@@ -54,11 +59,6 @@ public class ConfigurationManager {
 	 **/
 	private static final Logger log = LoggerFactory.getLogger(ConfigurationManager.class);
 
-	/**
-	 * An empty property entry
-	 */
-	private static final String STRING_EMPTY = "";
-
 	private String configurationFile = Constants.DEFAULT_CONFIG_FILENAME;
 
 	private boolean loaded = false;
@@ -283,6 +283,8 @@ public class ConfigurationManager {
 		loaded = true;
 	}
 
+	private void setProperty(Properties props, @Nonnull String key, @Nonnull String value) { props.setProperty(key, value); }
+	private void setPropertyIfNotNull(Properties props, @Nonnull String key, @CheckForNull String value) { if (value != null) setProperty(props, key, value); }
 	/* save to file */
 	public void saveToDisk() throws IOException {
 		String filename = this.getConfigurationFileName();
@@ -291,101 +293,90 @@ public class ConfigurationManager {
 		Properties props = new Properties();
 		props.clear();
 
-		props.setProperty(Constants.CFG_BKU, getDefaultBKUPersistent().toString());
+		setProperty(props, Constants.CFG_BKU, ISNOTNULL(getDefaultBKUPersistent().name()));
 
-		String proxyHost = getProxyHostPersistent();
-		if (proxyHost != STRING_EMPTY)
-			props.setProperty(Constants.CFG_PROXY_HOST, proxyHost);
+		setPropertyIfNotNull(props, Constants.CFG_PROXY_HOST, getProxyHostPersistent());
 		int proxyPort = getProxyPortPersistent();
 		if (proxyPort != -1)
-			props.setProperty(Constants.CFG_PROXY_PORT,Integer.toString(proxyPort));
-		String proxyUser = getProxyUserPersistent();
-		if (proxyUser != STRING_EMPTY)
-			props.setProperty(Constants.CFG_PROXY_USER, proxyUser);
-		String proxyPass = getProxyPassPersistent();
-		if (proxyPass != STRING_EMPTY)
-			props.setProperty(Constants.CFG_PROXY_PASS, proxyPass);
-
-		props.setProperty(Constants.CFG_EMBLEM, getDefaultEmblemPersistent());
-		props.setProperty(Constants.CFG_LOGO_ONLY_SIZE, Double.toString(getLogoOnlyTargetSize()));
-		props.setProperty(Constants.CFG_SIGNATURE_NOTE, getSignatureNote());
-		props.setProperty(Constants.CFG_MOBILE_NUMBER, getDefaultMobileNumberPersistent());
+			setProperty(props, Constants.CFG_PROXY_PORT, ISNOTNULL(Integer.toString(proxyPort)));
+		setPropertyIfNotNull(props, Constants.CFG_PROXY_USER, getProxyUserPersistent());
+		setPropertyIfNotNull(props, Constants.CFG_PROXY_PASS, getProxyPassPersistent());
+
+		setPropertyIfNotNull(props, Constants.CFG_EMBLEM, getDefaultEmblemPersistent());
+		setProperty(props, Constants.CFG_LOGO_ONLY_SIZE, ISNOTNULL(Double.toString(getLogoOnlyTargetSize())));
+		
+		setPropertyIfNotNull(props, Constants.CFG_SIGNATURE_NOTE, getSignatureNote());
+		setPropertyIfNotNull(props, Constants.CFG_MOBILE_NUMBER, getDefaultMobileNumberPersistent());
 		if (getRememberMobilePassword())
-			props.setProperty(Constants.CFG_MOBILE_PASSWORD_REMEMBER, Constants.TRUE);
-		props.setProperty(Constants.CFG_OUTPUT_FOLDER, getDefaultOutputFolderPersistent());
-		props.setProperty(Constants.CFG_POSTFIX, getSaveFilePostFix());
+			setProperty(props, Constants.CFG_MOBILE_PASSWORD_REMEMBER, Constants.TRUE);
+		setPropertyIfNotNull(props, Constants.CFG_OUTPUT_FOLDER, getDefaultOutputFolderPersistent());
+		setProperty(props, Constants.CFG_POSTFIX, getSaveFilePostFix());
 
 		Point size = this.configuration.mainWindowSize;
-		props.setProperty(Constants.CFG_MAINWINDOW_SIZE, size.x + "," + size.y);
+		setProperty(props, Constants.CFG_MAINWINDOW_SIZE, size.x + "," + size.y);
 
 		Locale configLocale = getInterfaceLocale();
 		if(configLocale != null) {
-			props.setProperty(Constants.CFG_LOCALE, LocaleSerializer.getParsableString(configLocale));
+			setProperty(props, Constants.CFG_LOCALE, LocaleSerializer.getParsableString(configLocale));
 		}
 
 		Locale signatureLocale = this.getSignatureLocale();
 		if(signatureLocale != null) {
-			props.setProperty(Constants.CFG_SIGNATURE_LOCALE, LocaleSerializer.getParsableString(signatureLocale));
+			setProperty(props, Constants.CFG_SIGNATURE_LOCALE, LocaleSerializer.getParsableString(signatureLocale));
 		}
 
 		if (getUseMarker())
-			props.setProperty(Constants.CFG_USE_MARKER, Constants.TRUE);
+			setProperty(props, Constants.CFG_USE_MARKER, Constants.TRUE);
 
 		if (getUseSignatureFields()) {
-			props.setProperty(Constants.CFG_USE_SIGNATURE_FIELDS, Constants.TRUE);
+			setProperty(props, Constants.CFG_USE_SIGNATURE_FIELDS, Constants.TRUE);
 		}
 
 		if (getEnablePlaceholderUsage()) {
-			props.setProperty(Constants.CFG_ENABLE_PLACEHOLDER, Constants.TRUE);
+			setProperty(props, Constants.CFG_ENABLE_PLACEHOLDER, Constants.TRUE);
 		}
 
 		if (getSignaturePdfACompat())
-			props.setProperty(Constants.CFG_SIGNATURE_PDFA_COMPAT, Constants.TRUE);
+			setProperty(props, Constants.CFG_SIGNATURE_PDFA_COMPAT, Constants.TRUE);
 
 		if (!getAutoPositionSignaturePersistent())
-			props.setProperty(Constants.CFG_SIGNATURE_POSITION, "");
+			setProperty(props, Constants.CFG_SIGNATURE_POSITION, "");
 		else
-			props.setProperty(Constants.CFG_SIGNATURE_POSITION, "auto");
+			setProperty(props, Constants.CFG_SIGNATURE_POSITION, "auto");
 
 		if (Constants.THEME != Constants.Themes.DEFAULT)
-			props.setProperty(Constants.CFG_THEME, Constants.THEME.name());
+			setProperty(props, Constants.CFG_THEME, ISNOTNULL(Constants.THEME.name()));
 
 		if (getKeyStoreEnabledPersistent())
-			props.setProperty(Constants.CFG_KEYSTORE_ENABLED, Constants.TRUE);
-		String keystoreFile = getKeyStoreFilePersistent();
-		if (keystoreFile != STRING_EMPTY)
-			props.setProperty(Constants.CFG_KEYSTORE_FILE, keystoreFile);
-		String keystoreType = getKeyStoreTypePersistent();
-		if (keystoreType != STRING_EMPTY)
-			props.setProperty(Constants.CFG_KEYSTORE_TYPE, keystoreType);
-		String keystoreAlias = getKeyStoreAliasPersistent();
-		if (keystoreAlias != STRING_EMPTY)
-			props.setProperty(Constants.CFG_KEYSTORE_ALIAS, keystoreAlias);
+			setProperty(props, Constants.CFG_KEYSTORE_ENABLED, Constants.TRUE);
+		setPropertyIfNotNull(props, Constants.CFG_KEYSTORE_FILE, getKeyStoreFilePersistent());
+		setPropertyIfNotNull(props, Constants.CFG_KEYSTORE_TYPE, getKeyStoreTypePersistent());
+		setPropertyIfNotNull(props, Constants.CFG_KEYSTORE_ALIAS, getKeyStoreAliasPersistent());
 
 		KeyStorePassStorageType keystorePassStorageType = getKeyStorePassStorageType();
 		if (keystorePassStorageType == null)
-			props.setProperty(Constants.CFG_KEYSTORE_PASSSTORETYPE, "none");
+			setProperty(props, Constants.CFG_KEYSTORE_PASSSTORETYPE, "none");
 		else if (keystorePassStorageType == KeyStorePassStorageType.MEMORY)
-			props.setProperty(Constants.CFG_KEYSTORE_PASSSTORETYPE, "memory");
+			setProperty(props, Constants.CFG_KEYSTORE_PASSSTORETYPE, "memory");
 		else if (keystorePassStorageType == KeyStorePassStorageType.DISK)
-			props.setProperty(Constants.CFG_KEYSTORE_PASSSTORETYPE, "disk");
+			setProperty(props, Constants.CFG_KEYSTORE_PASSSTORETYPE, "disk");
 
 		if (keystorePassStorageType == KeyStorePassStorageType.DISK)
 		{
 			String keystoreStorePass = getKeyStoreStorePassPersistent();
 			if (keystoreStorePass == null)
-				keystoreStorePass = STRING_EMPTY;
-			props.setProperty(Constants.CFG_KEYSTORE_STOREPASS, keystoreStorePass);
+				keystoreStorePass = "";
+			setProperty(props, Constants.CFG_KEYSTORE_STOREPASS, keystoreStorePass);
 			String keystoreKeyPass = getKeyStoreKeyPassPersistent();
 			if (keystoreKeyPass == null)
-				keystoreKeyPass = STRING_EMPTY;
-			props.setProperty(Constants.CFG_KEYSTORE_KEYPASS, keystoreKeyPass);
+				keystoreKeyPass = "";
+			setProperty(props, Constants.CFG_KEYSTORE_KEYPASS, keystoreKeyPass);
 		}
 
 		if (!getUpdateCheck())
-			props.setProperty(Constants.CFG_UPDATE_CHECK, Constants.FALSE);
+			setProperty(props, Constants.CFG_UPDATE_CHECK, Constants.FALSE);
 
-		props.setProperty(Constants.SIGNATURE_PROFILE, getSignatureProfile().name());
+		setProperty(props, Constants.SIGNATURE_PROFILE, ISNOTNULL(getSignatureProfile().name()));
 
 
 		FileOutputStream outputstream = new FileOutputStream(configFile, false);
@@ -395,6 +386,8 @@ public class ConfigurationManager {
 		log.info("Configuration file saved to " + configFile.getAbsolutePath());
 	}
 
+	static private <T> T fallThroughOnNull(T one, T two) { return (one != null) ? one : two; }
+
 	public void setConfigurationFileName(String configurationFile)
 	{
 		if (this.configurationFile.equals(configurationFile))
@@ -405,22 +398,22 @@ public class ConfigurationManager {
 	}
 	public String getConfigurationFileName() { return this.configurationFile; }
 
-	public void setDefaultBKUPersistent(BKUs bku) {
+	public void setDefaultBKUPersistent(@Nonnull BKUs bku) {
 		this.configuration.defaultBKU = bku;
 	}
 
-	public void setDefaultBKUOverlay(BKUs bku) {
+	public void setDefaultBKUOverlay(@Nonnull BKUs bku) {
 		this.configurationOverlay.defaultBKU = bku;
 	}
 
-	public BKUs getDefaultBKU() {
+	public @Nonnull BKUs getDefaultBKU() {
 		BKUs bku = this.configurationOverlay.defaultBKU;
 		if (bku == BKUs.NONE)
 			bku = getDefaultBKUPersistent();
 		return bku;
 	}
 
-	public BKUs getDefaultBKUPersistent() {
+	public @Nonnull BKUs getDefaultBKUPersistent() {
 		return this.configuration.defaultBKU;
 	}
 
@@ -442,7 +435,7 @@ public class ConfigurationManager {
 
 	public void setDefaultMobileNumberPersistent(String number) {
 		if (number == null || number.trim().isEmpty()) {
-			this.configuration.setMobileNumber(STRING_EMPTY);
+			this.configuration.setMobileNumber(null);
 		} else {
 			this.configuration.setMobileNumber(number);
 		}
@@ -450,35 +443,29 @@ public class ConfigurationManager {
 
 	public void setDefaultMobileNumberOverlay(String number) {
 		if (number == null || number.trim().isEmpty()) {
-			this.configurationOverlay.setMobileNumber(STRING_EMPTY);
+			this.configurationOverlay.setMobileNumber(null);
 		} else {
 			this.configurationOverlay.setMobileNumber(number);
 		}
 	}
 
-	public String getDefaultMobileNumber() {
-		String number = this.configurationOverlay.getMobileNumber();
-		if (number == null)
-			number = getDefaultMobileNumberPersistent();
-		return number;
+	public @CheckForNull String getDefaultMobileNumber() {
+		return fallThroughOnNull(this.configurationOverlay.getMobileNumber(), getDefaultMobileNumberPersistent());
 	}
 
-	public String getDefaultMobileNumberPersistent() {
-		String number = this.configuration.getMobileNumber();
-		if (number == null)
-			number = STRING_EMPTY;
-		return number;
+	public @CheckForNull String getDefaultMobileNumberPersistent() {
+		return this.configuration.getMobileNumber();
 	}
 
 	public void setDefaultMobilePasswordOverlay(String password) {
 		if (password == null || password.trim().isEmpty()) {
-			this.configurationOverlay.mobilePassword = STRING_EMPTY;
+			this.configurationOverlay.mobilePassword = null;
 		} else {
 			this.configurationOverlay.mobilePassword = password;
 		}
 	}
 
-	public String getDefaultMobilePassword() {
+	public @CheckForNull String getDefaultMobilePassword() {
 		/* this does not exist as a permanent config variable */
 		return this.configurationOverlay.mobilePassword;
 	}
@@ -494,14 +481,14 @@ public class ConfigurationManager {
 	public void setDefaultEmblemPersistent(String emblem) {
 		try {
 			if (emblem == null || emblem.trim().isEmpty()) {
-				this.configuration.setEmblem(STRING_EMPTY);
+				this.configuration.setEmblem(null);
 			} else {
 				this.configuration.setEmblem(emblem);
 			}
 		} catch (InvalidEmblemFile e) {
 			log.error("Error setting emblem file", e);
 			try {
-				this.configuration.setEmblem(STRING_EMPTY);
+				this.configuration.setEmblem(null);
 			} catch (InvalidEmblemFile e1) {
 				// Ignore
 			}
@@ -511,32 +498,26 @@ public class ConfigurationManager {
 	public void setDefaultEmblemOverlay(String emblem) {
 		try {
 			if (emblem == null || emblem.trim().isEmpty()) {
-				this.configurationOverlay.setEmblem(STRING_EMPTY);
+				this.configurationOverlay.setEmblem(null);
 			} else {
 				this.configurationOverlay.setEmblem(emblem);
 			}
 		} catch (InvalidEmblemFile e) {
 			log.error("Error setting emblem file", e);
 			try {
-				this.configurationOverlay.setEmblem(STRING_EMPTY);
+				this.configurationOverlay.setEmblem(null);
 			} catch (InvalidEmblemFile e1) {
 				// Ignore
 			}
 		}
 	}
 
-	public String getDefaultEmblemPath() {
-		String emblem = this.configurationOverlay.getEmblemPath();
-		if (emblem == null)
-			emblem = getDefaultEmblemPersistent();
-		return emblem;
+	public @CheckForNull String getDefaultEmblemPath() {
+		return fallThroughOnNull(this.configurationOverlay.getEmblemPath(), getDefaultEmblemPersistent());
 	}
 
-	public String getDefaultEmblemPersistent() {
-		String emblem = this.configuration.getEmblemPath();
-		if (emblem == null)
-			emblem = STRING_EMPTY;
-		return emblem;
+	public @CheckForNull String getDefaultEmblemPersistent() {
+		return this.configuration.getEmblemPath();
 	}
 
 	public void setLogoOnlyTargetSizePersistent(double v) {
@@ -549,7 +530,7 @@ public class ConfigurationManager {
 
 	public void setProxyHostPersistent(String host) {
 		if (host == null || host.trim().isEmpty()) {
-			this.configuration.proxyHost = STRING_EMPTY;
+			this.configuration.proxyHost = null;
 		} else {
 			this.configuration.proxyHost = host;
 		}
@@ -557,24 +538,18 @@ public class ConfigurationManager {
 
 	public void setProxyHostOverlay(String host) {
 		if (host == null || host.trim().isEmpty()) {
-			this.configurationOverlay.proxyHost = STRING_EMPTY;
+			this.configurationOverlay.proxyHost = null;
 		} else {
 			this.configurationOverlay.proxyHost = host;
 		}
 	}
 
-	public String getProxyHost() {
-		String host = this.configurationOverlay.proxyHost;
-		if (host == null)
-			host = getProxyHostPersistent();
-		return host;
+	public @CheckForNull String getProxyHost() {
+		return fallThroughOnNull(this.configurationOverlay.proxyHost, getProxyHostPersistent());
 	}
 
-	public String getProxyHostPersistent() {
-		String host = this.configuration.proxyHost;
-		if (host == null)
-			host = STRING_EMPTY;
-		return host;
+	public @CheckForNull String getProxyHostPersistent() {
+		return this.configuration.proxyHost;
 	}
 
 	public void setProxyPortPersistent(int port) {
@@ -597,7 +572,7 @@ public class ConfigurationManager {
 
 	public int getProxyPort() {
 		int port = this.configurationOverlay.getProxyPort();
-		if (port == -1)
+		if (port == -1) // TODO -1 is a terrible, no good, very bad hack
 			port = getProxyPortPersistent();
 		return port;
 	}
@@ -608,7 +583,7 @@ public class ConfigurationManager {
 
 	public void setProxyUserPersistent(String user) {
 		if (user == null || user.trim().isEmpty()) {
-			this.configuration.proxyUser = STRING_EMPTY;
+			this.configuration.proxyUser = null;
 		} else {
 			this.configuration.proxyUser = user;
 		}
@@ -616,29 +591,23 @@ public class ConfigurationManager {
 
 	public void setProxyUserOverlay(String user) {
 		if (user == null || user.trim().isEmpty()) {
-			this.configurationOverlay.proxyUser = STRING_EMPTY;
+			this.configurationOverlay.proxyUser = null;
 		} else {
 			this.configurationOverlay.proxyUser = user;
 		}
 	}
 
-	public String getProxyUser() {
-		String user = this.configurationOverlay.proxyUser;
-		if (user == null)
-			user = getProxyUserPersistent();
-		return user;
+	public @CheckForNull String getProxyUser() {
+		return fallThroughOnNull(this.configurationOverlay.proxyUser, getProxyUserPersistent());
 	}
 
-	public String getProxyUserPersistent() {
-		String user = this.configuration.proxyUser;
-		if (user == null)
-			user = STRING_EMPTY;
-		return user;
+	public @CheckForNull String getProxyUserPersistent() {
+		return this.configuration.proxyUser;
 	}
 
 	public void setProxyPassPersistent(String pass) {
 		if (pass == null || pass.trim().isEmpty()) {
-			this.configuration.proxyPass = STRING_EMPTY;
+			this.configuration.proxyPass = null;
 		} else {
 			this.configuration.proxyPass = pass;
 		}
@@ -646,29 +615,23 @@ public class ConfigurationManager {
 
 	public void setProxyPassOverlay(String pass) {
 		if (pass == null || pass.trim().isEmpty()) {
-			this.configurationOverlay.proxyPass = STRING_EMPTY;
+			this.configurationOverlay.proxyPass = null;
 		} else {
 			this.configurationOverlay.proxyPass = pass;
 		}
 	}
 
-	public String getProxyPass() {
-		String pass = this.configurationOverlay.proxyPass;
-		if (pass == null)
-			pass = getProxyPassPersistent();
-		return pass;
+	public @CheckForNull String getProxyPass() {
+		return fallThroughOnNull(this.configurationOverlay.proxyPass, getProxyPassPersistent());
 	}
 
-	public String getProxyPassPersistent() {
-		String pass = this.configuration.proxyPass;
-		if (pass == null)
-			pass = STRING_EMPTY;
-		return pass;
+	public @CheckForNull String getProxyPassPersistent() {
+		return this.configuration.proxyPass;
 	}
 
 	public void setDefaultOutputFolderPersistent(String outputFolder) {
 		if (outputFolder == null || outputFolder.trim().isEmpty()) {
-			this.configuration.outputFolder = STRING_EMPTY;
+			this.configuration.outputFolder = null;
 		} else {
 			this.configuration.outputFolder = outputFolder;
 		}
@@ -676,39 +639,30 @@ public class ConfigurationManager {
 
 	public void setDefaultOutputFolderOverlay(String outputFolder) {
 		if (outputFolder == null || outputFolder.trim().isEmpty()) {
-			this.configurationOverlay.outputFolder = STRING_EMPTY;
+			this.configurationOverlay.outputFolder = null;
 		} else {
 			this.configurationOverlay.outputFolder = outputFolder;
 		}
 	}
 
-	public String getDefaultOutputFolder() {
-		String outputFolder = this.configurationOverlay.outputFolder;
-		if (outputFolder == null)
-			outputFolder = getDefaultOutputFolderPersistent();
-		return outputFolder;
+	public @CheckForNull String getDefaultOutputFolder() {
+		return fallThroughOnNull(this.configurationOverlay.outputFolder, getDefaultOutputFolderPersistent());
 	}
 
-	public String getDefaultOutputFolderPersistent() {
-		String outputFolder = this.configuration.outputFolder;
-		if (outputFolder == null)
-			outputFolder = STRING_EMPTY;
-		return outputFolder;
+	public @CheckForNull String getDefaultOutputFolderPersistent() {
+		return this.configuration.outputFolder;
 	}
 
 	public void setSignatureNotePersistent(String note) {
 		if (note == null || note.trim().isEmpty()) {
-			this.configuration.signatureNote = STRING_EMPTY;
+			this.configuration.signatureNote = null;
 		} else {
 			this.configuration.signatureNote = note;
 		}
 	}
 
-	public String getSignatureNote() {
-		String note = this.configuration.signatureNote;
-		if (note == null)
-			note = STRING_EMPTY;
-		return note;
+	public @CheckForNull String getSignatureNote() {
+		return this.configuration.signatureNote;
 	}
 
 	public void setInterfaceLocalePersistent(Locale locale) {
@@ -721,7 +675,7 @@ public class ConfigurationManager {
 		}
 	}
 
-	public Locale getInterfaceLocale() {
+	public @Nonnull Locale getInterfaceLocale() {
 		Locale locale = this.configuration.interfaceLocale;
 		if (locale == null)
 			locale = Messages.getDefaultLocale();
@@ -736,7 +690,7 @@ public class ConfigurationManager {
 		}
 	}
 
-	public Locale getSignatureLocale() {
+	public @Nonnull Locale getSignatureLocale() {
 		Locale locale = this.configuration.signatureLocale;
 		if (locale == null)
 			locale = Messages.getDefaultLocale();
@@ -759,23 +713,17 @@ public class ConfigurationManager {
 		this.configurationOverlay.keystoreEnabled = enabled;
 	}
 
-	public Boolean getKeyStoreEnabled() {
-		Boolean enabled = this.configurationOverlay.keystoreEnabled;
-		if (enabled == null)
-			enabled = getKeyStoreEnabledPersistent();
-		return enabled;
+	public boolean getKeyStoreEnabled() {
+		return ISNOTNULL(fallThroughOnNull(this.configurationOverlay.keystoreEnabled, getKeyStoreEnabledPersistent()));
 	}
 
-	public Boolean getKeyStoreEnabledPersistent() {
-		Boolean enabled = this.configuration.keystoreEnabled;
-		if (enabled == null)
-			enabled = false;
-		return enabled;
+	public boolean getKeyStoreEnabledPersistent() {
+		return ISNOTNULL(fallThroughOnNull(this.configuration.keystoreEnabled, Boolean.FALSE));
 	}
 
 	public void setKeyStoreFilePersistent(String file) {
 		if (file == null || file.trim().isEmpty()) {
-			this.configuration.keystoreFile = STRING_EMPTY;
+			this.configuration.keystoreFile = null;
 		} else {
 			this.configuration.keystoreFile = file;
 		}
@@ -783,29 +731,23 @@ public class ConfigurationManager {
 
 	public void setKeyStoreFileOverlay(String file) {
 		if (file == null || file.trim().isEmpty()) {
-			this.configurationOverlay.keystoreFile = STRING_EMPTY;
+			this.configurationOverlay.keystoreFile = null;
 		} else {
 			this.configurationOverlay.keystoreFile = file;
 		}
 	}
 
-	public String getKeyStoreFile() {
-		String file = this.configurationOverlay.keystoreFile;
-		if (file == null)
-			file = getKeyStoreFilePersistent();
-		return file;
+	public @CheckForNull String getKeyStoreFile() {
+		return fallThroughOnNull(this.configurationOverlay.keystoreFile, getKeyStoreFilePersistent());
 	}
 
-	public String getKeyStoreFilePersistent() {
-		String file = this.configuration.keystoreFile;
-		if (file == null)
-			file = STRING_EMPTY;
-		return file;
+	public @CheckForNull String getKeyStoreFilePersistent() {
+		return this.configuration.keystoreFile;
 	}
 
 	public void setKeyStoreTypePersistent(String type) {
 		if (type == null || type.trim().isEmpty()) {
-			this.configuration.keystoreType = STRING_EMPTY;
+			this.configuration.keystoreType = null;
 		} else {
 			this.configuration.keystoreType = type;
 		}
@@ -813,29 +755,23 @@ public class ConfigurationManager {
 
 	public void setKeyStoreTypeOverlay(String type) {
 		if (type == null || type.trim().isEmpty()) {
-			this.configurationOverlay.keystoreType = STRING_EMPTY;
+			this.configurationOverlay.keystoreType = null;
 		} else {
 			this.configurationOverlay.keystoreType = type;
 		}
 	}
 
-	public String getKeyStoreType() {
-		String type = this.configurationOverlay.keystoreType;
-		if (type == null)
-			type = getKeyStoreTypePersistent();
-		return type;
+	public @CheckForNull String getKeyStoreType() {
+		return fallThroughOnNull(this.configurationOverlay.keystoreType, getKeyStoreTypePersistent());
 	}
 
-	public String getKeyStoreTypePersistent() {
-		String type = this.configuration.keystoreType;
-		if (type == null)
-			type = STRING_EMPTY;
-		return type;
+	public @CheckForNull String getKeyStoreTypePersistent() {
+		return this.configuration.keystoreType;
 	}
 
 	public void setKeyStoreAliasPersistent(String alias) {
 		if (alias == null || alias.trim().isEmpty()) {
-			this.configuration.keystoreAlias = STRING_EMPTY;
+			this.configuration.keystoreAlias = null;
 		} else {
 			this.configuration.keystoreAlias = alias;
 		}
@@ -843,24 +779,18 @@ public class ConfigurationManager {
 
 	public void setKeyStoreAliasOverlay(String alias) {
 		if (alias == null || alias.trim().isEmpty()) {
-			this.configurationOverlay.keystoreAlias = STRING_EMPTY;
+			this.configurationOverlay.keystoreAlias = null;
 		} else {
 			this.configurationOverlay.keystoreAlias = alias;
 		}
 	}
 
-	public String getKeyStoreAlias() {
-		String alias = this.configurationOverlay.keystoreAlias;
-		if (alias == null)
-			alias = getKeyStoreAliasPersistent();
-		return alias;
+	public @CheckForNull String getKeyStoreAlias() {
+		return fallThroughOnNull(this.configurationOverlay.keystoreAlias, getKeyStoreAliasPersistent());
 	}
 
-	public String getKeyStoreAliasPersistent() {
-		String alias = this.configuration.keystoreAlias;
-		if (alias == null)
-			alias = STRING_EMPTY;
-		return alias;
+	public @CheckForNull String getKeyStoreAliasPersistent() {
+		return this.configuration.keystoreAlias;
 	}
 
 	public void setKeyStorePassStorageTypePersistent(KeyStorePassStorageType type) {
@@ -879,7 +809,7 @@ public class ConfigurationManager {
 		this.configurationOverlay.keystoreStorePass = storePass;
 	}
 
-	public String getKeyStoreStorePass() {
+	public @CheckForNull String getKeyStoreStorePass() {
 		String storePass = this.configurationOverlay.keystoreStorePass;
 		if (storePass != null)
 			return storePass;
@@ -888,7 +818,7 @@ public class ConfigurationManager {
 		return getKeyStoreStorePassPersistent();
 	}
 
-	public String getKeyStoreStorePassPersistent() {
+	public @CheckForNull String getKeyStoreStorePassPersistent() {
 		return this.configuration.keystoreStorePass;
 	}
 
@@ -900,7 +830,7 @@ public class ConfigurationManager {
 		this.configurationOverlay.keystoreKeyPass = keyPass;
 	}
 
-	public String getKeyStoreKeyPass() {
+	public @CheckForNull String getKeyStoreKeyPass() {
 		String keyPass = this.configurationOverlay.keystoreKeyPass;
 		if (keyPass != null)
 			return keyPass;
@@ -909,7 +839,7 @@ public class ConfigurationManager {
 		return getKeyStoreKeyPassPersistent();
 	}
 
-	public String getKeyStoreKeyPassPersistent() {
+	public @CheckForNull String getKeyStoreKeyPassPersistent() {
 		return this.configuration.keystoreKeyPass;
 	}
 
@@ -921,11 +851,11 @@ public class ConfigurationManager {
 		return this.configuration.updateCheck;
 	}
 
-	public void setMainWindowSizePersistent(Point size) {
+	public void setMainWindowSizePersistent(@Nonnull Point size) {
 		this.configuration.mainWindowSize = size;
 	}
 
-	public Point getMainWindowSize() {
+	public @Nonnull Point getMainWindowSize() {
 		return this.configuration.mainWindowSize;
 	}
 
@@ -955,20 +885,20 @@ public class ConfigurationManager {
 		if (useMarker) setUseSignatureFieldsPersistent(false);
 	}
 
-    public void setSaveFilePostFixPersistent(String postFix) {
+    public void setSaveFilePostFixPersistent(@Nonnull String postFix) {
         this.configuration.saveFilePostFix = postFix;
     }
 
-	public String getSaveFilePostFix(){
+	public @Nonnull String getSaveFilePostFix(){
 		return this.configuration.saveFilePostFix;
 	}
 
-	public Profile getSignatureProfile() {
-		return this.configuration.getSignatureProfile();
+	public @Nonnull Profile getSignatureProfile() {
+		return ISNOTNULL(fallThroughOnNull(this.configuration.signatureProfile, Profile.SIGNATURBLOCK_SMALL));
 	}
 
 	public void setSignatureProfilePersistent(Profile profile) {
-		this.configuration.setSignatureProfile(profile);
+		this.configuration.signatureProfile = profile;
 	}
 
 	public void setEnablePlaceholderUsagePersistent(boolean bool) {
diff --git a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/states/PrepareSigningState.java b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/states/PrepareSigningState.java
index 132a134b..1669f2f8 100644
--- a/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/states/PrepareSigningState.java
+++ b/pdf-over-gui/src/main/java/at/asit/pdfover/gui/workflow/states/PrepareSigningState.java
@@ -228,7 +228,7 @@ public class PrepareSigningState extends State {
 				this.setNextState(new KSState(getStateMachine()));
 				break;
 			default:
-				log.error("Invalid selected BKU Value \"NONE\" in PrepareSigningState!");
+				log.error("Invalid selected BKU Value \"{}\" in PrepareSigningState!", status.bku.name());
 				this.setNextState(new BKUSelectionState(getStateMachine()));
 		}
 	}
diff --git a/pdf-over-signer/src/main/java/at/asit/pdfover/signer/Emblem.java b/pdf-over-signer/src/main/java/at/asit/pdfover/signer/Emblem.java
index c045169a..6c368b16 100644
--- a/pdf-over-signer/src/main/java/at/asit/pdfover/signer/Emblem.java
+++ b/pdf-over-signer/src/main/java/at/asit/pdfover/signer/Emblem.java
@@ -85,7 +85,7 @@ public class Emblem {
 		this.originalFileName = filename;
 	}
 
-	private String getFileHash(String filename) throws IOException {
+	private static String getFileHash(String filename) throws IOException {
 		InputStream is = Files.newInputStream(Path.of(filename));
 		return DigestUtils.md5Hex(is);
 	}