Add missing JavaDoc.

guacamole-ext/src/main/java/net/sourceforge/guacamole/net/auth/Credentials.java

@@ -52,6 +52,9 @@ import javax.servlet.http.HttpSession;
  */
 public class Credentials implements Serializable {
 
+    /**
+     * Unique identifier associated with this specific version of Credentials.
+     */
     private static final long serialVersionUID = 1L;
 
     /**

guacamole-ext/src/main/java/net/sourceforge/guacamole/net/auth/Directory.java

@@ -95,9 +95,7 @@ public interface Directory<IdentifierType, ObjectType> {
     
     /**
      * Updates the stored object with the data contained in the given object.
-     * The object to update is identified using the identifier given.
      * 
-     * @param identifier The identifier of the object to update.
      * @param object The object which will supply the data for the update.
      * 
      * @throws GuacamoleException If an error occurs while updating the object,

guacamole-ext/src/main/java/net/sourceforge/guacamole/properties/GuacamoleHome.java

@@ -46,6 +46,9 @@ import java.io.File;
  */
 public class GuacamoleHome {
 
+    /**
+     * GuacamoleHome is a utility class and cannot be instantiated.
+     */
     private GuacamoleHome() {}
     
     /**

guacamole-ext/src/main/java/net/sourceforge/guacamole/properties/GuacamoleProperties.java

@@ -58,6 +58,9 @@ import net.sourceforge.guacamole.GuacamoleServerException;
  */
 public class GuacamoleProperties {
 
+    /**
+     * GuacamoleProperties is a utility class and cannot be instantiated.
+     */
     private GuacamoleProperties() {}
 
     /**
@@ -81,7 +84,16 @@ public class GuacamoleProperties {
 
     };
 
+    /**
+     * All properties read from guacamole.properties when this class was first
+     * used.
+     */
     private static final Properties properties;
+
+    /**
+     * Any error encountered when reading guacamole.properties was last
+     * attempted.
+     */
     private static GuacamoleException exception;
 
     static {