fix doc warning in java retrofit2 client

modules/swagger-codegen/src/main/resources/Java/libraries/retrofit2/ApiClient.mustache

@@ -188,7 +188,7 @@ public class ApiClient {
 
     /**
      * Helper method to configure the token endpoint of the first oauth found in the apiAuthorizations (there should be only one)
-     * @return
+     * @return Token request builder
      */
     public TokenRequestBuilder getTokenEndPoint() {
         for(Interceptor apiAuthorization : apiAuthorizations.values()) {
@@ -202,7 +202,7 @@ public class ApiClient {
 
     /**
      * Helper method to configure authorization endpoint of the first oauth found in the apiAuthorizations (there should be only one)
-     * @return
+     * @return Authentication request builder
      */
     public AuthenticationRequestBuilder getAuthorizationEndPoint() {
         for(Interceptor apiAuthorization : apiAuthorizations.values()) {

modules/swagger-codegen/src/main/resources/Java/libraries/retrofit2/pom.mustache

@@ -68,6 +68,7 @@
       <plugin>
         <groupId>org.codehaus.mojo</groupId>
         <artifactId>build-helper-maven-plugin</artifactId>
+        <version>1.10</version>
         <executions>
           <execution>
             <id>add_sources</id>
@@ -152,6 +153,7 @@
     </dependency>
   </dependencies>
   <properties>
+    <project.build.sourceEncoding>UTF-8</project.build.sourceEncoding>
     <java.version>{{#java8}}1.8{{/java8}}{{^java8}}1.7{{/java8}}</java.version>
     <maven.compiler.source>${java.version}</maven.compiler.source>
     <maven.compiler.target>${java.version}</maven.compiler.target>