javax.ws.rs.core.PathSegment and Errai - java-ee-6

Question

Errai has support for JAX-RS, although when I tried to use it with the supplied Maven archetype GWT complained with the error:
No source code is available for type javax.ws.rs.core.PathSegment; did you forget to inherit a required module?
The PathSegment interface appears to be part of the official Java EE standard, so why is this class not available?

Answer 1

A solution is to create the javax.ws.rs.core package in your GWT project, and include the interfaces for yourself. These interfaces are MultivaluedMap:
package javax.ws.rs.core;
import java.util.List;
import java.util.Map;
/**
* A map of key-values pairs. Each key can have zero or more values.
*
*/
public interface MultivaluedMap<K, V> extends Map<K, List<V>> {
/**
* Set the key's value to be a one item list consisting of the supplied value.
* Any existing values will be replaced.
*
* #param key the key
* #param value the single value of the key
*/
void putSingle(K key, V value);
/**
* Add a value to the current list of values for the supplied key.
* #param key the key
* #param value the value to be added.
*/
void add(K key, V value);
/**
* A shortcut to get the first value of the supplied key.
* #param key the key
* #return the first value for the specified key or null if the key is
* not in the map.
*/
V getFirst(K key);
}
PathSegment:
package javax.ws.rs.core;
/**
* Represents a URI path segment and any associated matrix parameters. When an
* instance of this type is injected with {#link javax.ws.rs.PathParam}, the
* value of the annotation identifies which path segment is selected and the
* presence of an {#link javax.ws.rs.Encoded} annotation will result in an
* instance that supplies the path and matrix parameter values in
* URI encoded form.
*
* #see UriInfo#getPathSegments
* #see javax.ws.rs.PathParam
*/
public interface PathSegment
{
/**
* Get the path segment.
* <p/>
*
* #return the path segment
*/
String getPath();
/**
* Get a map of the matrix parameters associated with the path segment.
* The map keys are the names of the matrix parameters with any
* percent-escaped octets decoded.
*
* #return the map of matrix parameters
* #see Matrix URIs
*/
MultivaluedMap<String, String> getMatrixParameters();
}
You'll need a GWT module file (in the javax.ws.rs package):
<!DOCTYPE module PUBLIC "-//Google Inc.//DTD Google Web Toolkit 1.6//EN"
"http://google-web-toolkit.googlecode.com/svn/releases/1.6/distro-source/core/src/gwt-module.dtd">
<module rename-to="App">
<source path="core"/>
</module>
And you'll need to add an inherits reference to you application GWT module:
<!DOCTYPE module PUBLIC "-//Google Inc.//DTD Google Web Toolkit 1.6//EN"
"http://google-web-toolkit.googlecode.com/svn/releases/1.6/distro-source/core/src/gwt-module.dtd">
<module rename-to="App">
<inherits name='com.google.gwt.user.User'/>
<inherits name="org.jboss.errai.common.ErraiCommon"/>
<inherits name="org.jboss.errai.ioc.Container"/>
<inherits name="org.jboss.errai.enterprise.Jaxrs"/>
<inherits name="com.redhat.topicindex.rest"/>
<inherits name="javax.ws.rs.core"/>
</module>