docs: fix javadoc warnings

Close #141

Author: javier-godoy

src/main/java/com/flowingcode/vaadin/addons/googlemaps/GoogleMap.java

@@ -592,7 +592,7 @@ public boolean isBrowserHasGeolocationSupport() {
    * Adds a CurrentLocationEvent listener. The listener is called when setting the current location.
    *
    * @param listener
-   * @return
+   * @return a handle that can be used for removing the listener
    */
   public Registration addCurrentLocationEventListener(
       ComponentEventListener<CurrentLocationEvent> listener) {
@@ -604,7 +604,7 @@ public Registration addCurrentLocationEventListener(
    * found.
    *
    * @param listener
-   * @return
+   * @return a handle that can be used for removing the listener
    */
   public Registration addGeolocationErrorEventListener(
       ComponentEventListener<GeolocationErrorEvent> listener) {
@@ -705,7 +705,7 @@ public void setClusteringRenderer(String customRenderer) {
    * pan or zoom)
    *
    * @param listener
-   * @return
+   * @return a handle that can be used for removing the listener
    */
   public Registration addMapIdleListener(ComponentEventListener<GoogleMapIdleEvent> listener) {
     DomListenerRegistration registration =
@@ -726,7 +726,7 @@ public GoogleMapIdleEvent(GoogleMap source, boolean fromClient) {
    * zoomed
    *
    * @param listener
-   * @return
+   * @return a handle that can be used for removing the listener
    */
   public Registration addGoogleMapBoundsChangedListener(
       ComponentEventListener<GoogleMapBoundsChangedEvent> listener) {

src/main/java/com/flowingcode/vaadin/addons/googlemaps/GoogleMapPoly.java

@@ -182,7 +182,7 @@ public Registration addClickListener(
   }
 
   /**
-   * @deprecated, use {@link #setIcons(IconSequence...)} instead.
+   * @deprecated Use {@link #setIcons(IconSequence...)} instead.
    */
   @Deprecated
   public void setIcons(Icon... icons) {

src/main/java/com/flowingcode/vaadin/addons/googlemaps/Icon.java

@@ -7,9 +7,9 @@
  * Licensed under the Apache License, Version 2.0 (the "License");
  * you may not use this file except in compliance with the License.
  * You may obtain a copy of the License at
- * 
+ *
  *      http://www.apache.org/licenses/LICENSE-2.0
- * 
+ *
  * Unless required by applicable law or agreed to in writing, software
  * distributed under the License is distributed on an "AS IS" BASIS,
  * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
@@ -25,7 +25,7 @@
 import java.util.Optional;
 
 /**
- * @deprecated, use {@link IconSequence} instead.
+ * @deprecated Use {@link IconSequence} instead.
  */
 @Deprecated
 public class Icon extends Symbol {
@@ -34,9 +34,9 @@ public class Icon extends Symbol {
 
   public Icon(String path, String strokeColor, String fillColor, int fillOpacity, int repeat) {
     super(path);
-    this.setStrokeColor(strokeColor);
-    this.setFillColor(fillColor);
-    this.setFillOpacity(Double.valueOf(fillOpacity));
+    setStrokeColor(strokeColor);
+    setFillColor(fillColor);
+    setFillOpacity(Double.valueOf(fillOpacity));
     this.repeat = repeat;
   }