Fix some spotbugs issues

src/main/java/org/jabref/Globals.java

@@ -58,7 +58,7 @@ private Globals() {
     }
 
     // Key binding preferences
-    public static KeyBindingRepository getKeyPrefs() {
+    public static synchronized KeyBindingRepository getKeyPrefs() {
         if (keyBindingRepository == null) {
             keyBindingRepository = prefs.getKeyBindingRepository();
         }

src/main/java/org/jabref/gui/BasePanel.java

@@ -2144,7 +2144,9 @@ public void action() {
                 if ((focused != null) && (focused instanceof FieldEditor) && focused.hasFocus()) {
                     // User is currently editing a field:
                     // Check if it is the preamble:
-                    if ((preambleEditor != null) && (focused == preambleEditor.getFieldEditor())) {
+
+                    FieldEditor fieldEditor = (FieldEditor) focused;
+                    if ((preambleEditor != null) && (fieldEditor.equals(preambleEditor.getFieldEditor()))) {
                         preambleEditor.storeCurrentEdit();
                     }
                 }

src/main/java/org/jabref/gui/importer/actions/OpenDatabaseAction.java

@@ -150,8 +150,8 @@ public void openFiles(List<Path> filesToOpen, boolean raisePanel) {
             Path file = iterator.next();
             for (int i = 0; i < frame.getTabbedPane().getTabCount(); i++) {
                 BasePanel basePanel = frame.getBasePanelAt(i);
-                if ((basePanel.getBibDatabaseContext().getDatabaseFile().isPresent())
-                        && basePanel.getBibDatabaseContext().getDatabaseFile().get().equals(file)) {
+                if ((basePanel.getBibDatabaseContext().getDatabasePath().isPresent())
+                        && basePanel.getBibDatabaseContext().getDatabasePath().get().equals(file)) {
                     iterator.remove();
                     removed++;
                     // See if we removed the final one. If so, we must perhaps

src/main/java/org/jabref/logic/citationstyle/CitationStyle.java

@@ -163,16 +163,22 @@ public String toString() {
     }
 
     @Override
-    public boolean equals(Object other) {
-        if (this == other) {
+    public boolean equals(Object o) {
+        if (this == o) {
             return true;
         }
-        if (other == null || getClass() != other.getClass()) {
+        if ((o == null) || (getClass() != o.getClass())) {
             return false;
         }
 
-        CitationStyle that = (CitationStyle) other;
-        return source != null ? source.equals(that.source) : that.source == null;
+        CitationStyle other = (CitationStyle) o;
+        return Objects.equals(source, other.source);
+    }
+
+    @Override
+    public int hashCode()
+    {
+        return Objects.hash(source);
     }
 
 }

src/main/java/org/jabref/logic/importer/fetcher/MrDLibFetcher.java

@@ -118,10 +118,10 @@ private String constructQuery(String queryWithTitle) {
         URI uri = null;
         try {
             uri = builder.build();
+            return uri.toString();
         } catch (URISyntaxException e) {
             LOGGER.error(e.getMessage(), e);
         }
-        System.out.println("Query: " + uri.toString());
-        return uri.toString();
+        return "";
     }
 }

src/main/java/org/jabref/model/groups/WordKeywordGroup.java

@@ -23,8 +23,8 @@ public class WordKeywordGroup extends KeywordGroup implements GroupEntryChanger
     private final boolean onlySplitWordsAtSeparator;
 
     public WordKeywordGroup(String name, GroupHierarchyType context, String searchField,
-                            String searchExpression, boolean caseSensitive, Character keywordSeparator,
-                            boolean onlySplitWordsAtSeparator) {
+            String searchExpression, boolean caseSensitive, Character keywordSeparator,
+            boolean onlySplitWordsAtSeparator) {
         super(name, context, searchField, searchExpression, caseSensitive);
 
         this.keywordSeparator = keywordSeparator;
@@ -92,13 +92,13 @@ public boolean equals(Object o) {
             return false;
         }
         WordKeywordGroup other = (WordKeywordGroup) o;
-        return getName().equals(other.getName())
-                && (getHierarchicalContext() == other.getHierarchicalContext())
-                && searchField.equals(other.searchField)
-                && searchExpression.equals(other.searchExpression)
-                && (caseSensitive == other.caseSensitive)
-                && keywordSeparator == other.keywordSeparator
-                && onlySplitWordsAtSeparator == other.onlySplitWordsAtSeparator;
+        return Objects.equals(getName(), other.getName())
+                && Objects.equals(getHierarchicalContext(), other.getHierarchicalContext())
+                && Objects.equals(searchField, other.searchField)
+                && Objects.equals(searchExpression, other.searchExpression)
+                && Objects.equals(caseSensitive, other.caseSensitive)
+                && Objects.equals(keywordSeparator, other.keywordSeparator)
+                && Objects.equals(onlySplitWordsAtSeparator, other.onlySplitWordsAtSeparator);
     }
 
     @Override