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swagger-maven-plugin triggers Javadoc warning: element value must be a constant expression (but it is!) in Java annotation

Javadoc (via Maven) is giving me the following error in one my Java JAX-RS interface method signatures:
error: element value must be a constant expression
Here is my JAX-RS interface:
public interface FooResource {
#Consumes(APPLICATION_FORM_URLENCODED_UTF_8)
public void bar();
}
Javdoc gives the error for #Consumes. Here is the definition for APPLICATION_FORM_URLENCODED_UTF_8, which appears in MyAppConstants in the same project:
public static final String APPLICATION_FORM_URLENCODED_UTF_8 =
APPLICATION_FORM_URLENCODED + ";" + CHARSET_PARAMETER + "=UTF-8";
And here is the definition of APPLICATION_FORM_URLENCODED, which appears in javax.ws.rs.core.MediaType:
public final static String APPLICATION_FORM_URLENCODED = "application/x-www-form-urlencoded";
And here is the definition of CHARSET_PARAMETER, which also appears in javax.ws.rs.core.MediaType:
public static final String CHARSET_PARAMETER = "charset";
Now I ask you: what about APPLICATION_FORM_URLENCODED_UTF_8 is not constant at compile time?
The error message didn't say that I have to provide a literal. It said I had to provide a constant. So what about this is not a constant?
(I could almost swear that this worked at one time but suddenly stopped working.)
Update: Found cause, but still don't understand.
For some reason, merely including the swagger-maven-plugin in the POM will trigger this problem! My code doesn't change at all, but as soon as I add the following dependency, suddenly I get Javadoc warnings for my existing code!!!
<dependency>
<groupId>com.github.kongchen</groupId>
<artifactId>swagger-maven-plugin</artifactId>
<version>3.1.5</version>
</dependency>
How can a single dependency make Javadoc work differently on a code file? What is swagger-maven-plugin doing?

My best guess is that this happens because swagger-maven-plugin transitively (via io.swagger:swagger-core:1.5.13) an old version of the JAX-RS specification in javax.ws.rs:jsr311-api:1.1.1. Note that the JAX-RS 2 artifact ID is javax.ws.rs-api, Maven doesn't realize that they are different versions of the same JAR, and pulls them both in as dependencies. I can only guess that javax.ws.rs:jsr311-api in fact does not use constants for the variables in question. In any case, when I threw out swagger-maven-plugin and pulled in io.swagger:swagger-annotations (which was all I needed in this project for documentation), the problem went away.
See https://github.com/kongchen/swagger-maven-plugin/issues/543.

Use Errai Ui with GWT

I'd really like to use Errai UI(3.2.4) in my GWT (2.8) application. I already have one setup with an EntryPoint implementation and an onModuleLoad. I have restGWT setup and interacting with my server (which uses Jersey).
All of the documentation I find assumes that you are building a full-on Errai project, starting from scratch using the forge addon thing. I'm not. I just want to use the templating stuff and data-binding. I'm working with a barebones setup and I can't even make a label show in my app.
I have this GWT entry point:
public class App implements EntryPoint
{
#Inject
private ApplicationContainer applicationContainer;
public void onModuleLoad()
{
RootPanel.get("root").add(applicationContainer);
}
}
And the ApplicationContainer:
#Templated
public class ApplicationContainer extends Composite
{
#DataField
private Element applicationContainer = DOM.createDiv();
#PostConstruct
public void init()
{
GWT.log("Initializing");
}
}
And it's accompanying template:
<div id="applicationContainer" data-field="applicationContainer">
Application Container
</div>
I should see "Application Container" in the browser, but I get this error in the browser console:
ComplexPanel.java:96 Uncaught TypeError: Cannot read property 'removeFromParent_0_g$' of undefined
The widget and the template are named the same and in the same package. My widget is created just like the documentation shows: http://erraiframework.org/getting-started/index.html#ErraiUIPage
Can someone tell me what I'm missing here? Examples for this are very minimal, and they all assume a complete Errai project. Do I still need an #EntryPoint? Do I need #PostConstruct? Is Errai even designed to work like this?
Thanks for any help.

Yes, the #EntryPoint annotation is important and I'm not sure you'll be able to mix up part of this framework with some other approach. It doesn't mean you need to use all the modules, but you should rather follow the Errai's guidelines if about the part you use.
Please see example entry point here:
https://github.com/errai/errai/blob/3.2.4.Final/errai-demos/errai-jpa-demo-todo-list/src/main/java/org/jboss/errai/demo/todo/client/local/ClientEntryPoint.java
You'll find also more examples from the path .../3.2.4.Final/errai-demos/
Above is about Errai 3.x.
Please also note that Errai 4.x brings some changes if it is just about the Errai UI. It's nicely described here:
http://errai-blog.blogspot.com/2016/04/errai-400beta1-released.html
Now your #Templated bean do not need to extend Composite. The root element of the template is accessible as a #DataField etc.
Hope you'll find it helpful. Good luck!

The answer to your questions is here: https://github.com/errai/errai-tutorial
You basically need to migrate your app to use Maven so you get the dependencies right first, then use the POM in this project and snap it in your project.
Then you can include a Bootstrap file to add a #EntryPoint class however this is not necessary you can just add a Page in the client path e.g.:
com.mycompany.app.client
-->MyPage.html
-->MyPage.java
Where the java file here contains the default page, i.e.
#Dependent
#Templated
#Page(role = DefaultPage.class)
public class MyPage extends Composite{}

Explicit binding required with MapBinder - Guice 4.0 beta4

I tried to update my Guice version from 4.0-beta to 4.0-beta4 this morning and I started having problems with the MapBinder. I have a base module that extend JerseyServletModule. In the configureServlets() method, I do :
MapBinder<String, ExportData> exportDataMapBinder = MapBinder.newMapBinder(binder(),String.class,ExportData.class);
binder().requireExplicitBindings();
bindCommonServices();
install(new V8Module(exportDataMapBinder));
I populate the map in private modules, like this :
exportDataMapBinder.addBinding(VERSION).to(ExportDataV8.class);
ExportData is an interface and ExportDataV8 implements it (I won't paste them to keep the question short).
It worked just fine using guice 4.0-beta, but with guice 4.0-beta4, I started having errors like this :
1) Explicit bindings are required and com.coveo.ua.data.export.ExportData annotated with #com.google.inject.multibindings.Element(setName=, uniqueId=2, type=MAPBINDER) is not explicitly bound.
while locating com.coveo.ua.data.export.ExportData annotated with #com.google.inject.multibindings.Element(setName=, uniqueId=2, type=MAPBINDER)
at com.google.inject.multibindings.MapBinder$RealMapBinder$1.initialize(MapBinder.java:380)
at com.coveo.ua.config.UsageAnalyticsBaseModule.configureServlets(UsageAnalyticsBaseModule.java:223)
Anybody has an idea what I am doing wrong ?
Please tell me if I forgot to include important details.

I see from your example that you are setting that explict bindings are required for your main module. Just remove that method and it will surely work. Do not know what has been changed in 4.0-beta if that code worked before.
Your code:
MapBinder<String, ExportData> exportDataMapBinder = ...
binder().requireExplicitBindings();
Should probably remove this line:
binder().requireExplicitBindings();

I updated to Guice 4.0 beta 5 and it fixed my problem. As Tavian Barnes suggested. It was probably a bug with beta 4.

com.liferay.portlet.ActionResponseImpl cannot be cast to com.liferay.portlet.ActionResponseImpl

I tried to cast Action response like this:
private void mappingMethod(ActionResponse response) {
ActionResponseImpl actionResponseImpl = (ActionResponseImpl)response;
...}
In debugging on "Expression Evaluation" window I can see the type of "responce" is ActionResponseImpl, and cast does not cause exception. But on runtime I have this exeption:
java.lang.ClassCastException: com.liferay.portlet.ActionResponseImpl cannot be cast to com.liferay.portlet.ActionResponseImpl
Please tell me what is the problem.
P.S.: In PortalImpl class, the copyRequestParameters method has same string, but here it's working....

It would do you good if you refrained from using classes from portal-impl.jar in your custom plugin portlet.
ActionResponseImpl is a class in the portal-impl.jar. So if you can give a use-case as to why you are planning to use this class, then we can suggest alternative.

You have ActionResponseImpl twice on the classpath - what jars from Liferay did you include in your project? As Prakash mentions, it's portal-impl.jar, which you can not have in a plugin.
What the ClassCastException wants to tell you is that your class extends one implementation of ActionResponseImpl, but the runtime environments expects it to be another implementation - they might be identical, but as they are loaded from two different sources, the classloader cannot refer one to another superclass than it extends.

I saw this issue, when I call a method using Ajax from XHTML page. I modified my method to return simple string and removed the code that tries to modify the actionResponseImpl and that resolved the issue.

This type of errors are produced by different classloaders. A class is identified by their fully qualified class name AND its Classloader. So if you embedd portal-impl in your portlet; the action is going to receive an ActionResponseImpl instance from the portal classloader and is trying to cast this one to a class of your portlet class loader .
see more: http://www.javaspecialists.eu/archive/Issue018.html

#NotThreadSafe not found error

0.3 code.
#NotThreadSafe
public class VoicemailPlaybackFragment extends Fragment {
//
}
I am getting compile time error as "NotThreadSafe cannot be resolved to a type"
i.e, #NotThreadSafe not imported
can anyone help, thanks in advance.

That annotation is not in the standard Java or Android codebases yet.
Depending on how and why you are using this, you should either add some third-party JAR containing it to your classpath, or just add a copy to your codebase.
This page lists a few products that include the annotation.