Fix various code issues as detected by Sonar

Mostly minor changes:
- Add deprecated javadoc tag on deprecated members
- Reduce duplication (FlatFile, BackupService, ...)
- Make methods static
- Reduce size of anonymous classes
- Replace name with displayName in PermissionsSystemType (avoids confusing with Enum name())
- Tabs to spaces
- Merge if statements

Code from third-party sources (BCryptService, BinTools, PHPBB) not modified.

src/main/java/fr/xephi/authme/permission/AuthGroupHandler.java

@@ -31,7 +31,8 @@ public class AuthGroupHandler implements Reloadable {
     private String unregisteredGroup;
     private String registeredGroup;
 
-    AuthGroupHandler() { }
+    AuthGroupHandler() {
+    }
 
     /**
      * Set the group of a player, by its AuthMe group type.

src/main/java/fr/xephi/authme/permission/PermissionsManager.java

@@ -78,12 +78,12 @@ public class PermissionsManager implements Reloadable {
                 if (handler != null) {
                     // Show a success message and return
                     this.handler = handler;
-                    ConsoleLogger.info("Hooked into " + type.getName() + "!");
+                    ConsoleLogger.info("Hooked into " + type.getDisplayName() + "!");
                     return;
                 }
             } catch (Exception ex) {
                 // An error occurred, show a warning message
-                ConsoleLogger.logException("Error while hooking into " + type.getName(), ex);
+                ConsoleLogger.logException("Error while hooking into " + type.getDisplayName(), ex);
             }
         }
 
@@ -101,7 +101,7 @@ public class PermissionsManager implements Reloadable {
 
         // Make sure the plugin is enabled before hooking
         if (!plugin.isEnabled()) {
-            ConsoleLogger.info("Not hooking into " + type.getName() + " because it's disabled!");
+            ConsoleLogger.info("Not hooking into " + type.getDisplayName() + " because it's disabled!");
             return null;
         }
 
@@ -414,7 +414,7 @@ public class PermissionsManager implements Reloadable {
      */
     public boolean setGroups(Player player, List<String> groupNames) {
         // If no permissions system is used or if there's no group supplied, return false
-        if (!isEnabled() || groupNames.size() <= 0)
+        if (!isEnabled() || groupNames.isEmpty())
             return false;
 
         // Set the main group

src/main/java/fr/xephi/authme/permission/PermissionsSystemType.java

@@ -33,21 +33,21 @@ public enum PermissionsSystemType {
     /**
      * The display name of the permissions system.
      */
-    public String name;
+    private String displayName;
 
     /**
      * The name of the permissions system plugin.
      */
-    public String pluginName;
+    private String pluginName;
 
     /**
      * Constructor for PermissionsSystemType.
      *
-     * @param name       Display name of the permissions system.
+     * @param displayName Display name of the permissions system.
      * @param pluginName Name of the plugin.
      */
-    PermissionsSystemType(String name, String pluginName) {
-        this.name = name;
+    PermissionsSystemType(String displayName, String pluginName) {
+        this.displayName = displayName;
         this.pluginName = pluginName;
     }
 
@@ -56,8 +56,8 @@ public enum PermissionsSystemType {
      *
      * @return Display name.
      */
-    public String getName() {
-        return this.name;
+    public String getDisplayName() {
+        return this.displayName;
     }
 
     /**
@@ -76,7 +76,7 @@ public enum PermissionsSystemType {
      */
     @Override
     public String toString() {
-        return getName();
+        return getDisplayName();
     }
 
     /**

src/main/java/fr/xephi/authme/permission/handlers/BPermissionsHandler.java

@@ -55,7 +55,7 @@ public class BPermissionsHandler implements PermissionHandler {
         List<String> groups = getGroups(player);
 
         // Make sure there is any group available, or return null
-        if (groups.size() == 0)
+        if (groups.isEmpty())
             return null;
 
         // Return the first group

src/main/java/fr/xephi/authme/permission/handlers/PermissionsBukkitHandler.java

@@ -54,7 +54,7 @@ public class PermissionsBukkitHandler implements PermissionHandler {
         List<String> groups = getGroups(player);
 
         // Make sure there is any group available, or return null
-        if (groups.size() == 0)
+        if (groups.isEmpty())
             return null;
 
         // Return the first group

src/main/java/fr/xephi/authme/permission/handlers/PermissionsExHandler.java

@@ -77,7 +77,7 @@ public class PermissionsExHandler implements PermissionHandler {
         PermissionUser user = permissionManager.getUser(player);
 
         List<String> groups = user.getParentIdentifiers(null);
-        if (groups.size() == 0)
+        if (groups.isEmpty())
             return null;
 
         return groups.get(0);