Error Generating a Discovery Doc from a backend API - google-cloud-endpoints

Question

When executing this command from my ../war directory (from https://developers.google.com/appengine/docs/java/endpoints/endpoints_tool#generating_a_discovery_doc):
D:\programs\eclipse-kepler\plugins\com.google.appengine.eclipse.sdkbundle_1.9.4\appengine-java-sdk-1.9.4\bin\endpoints.cmd get-discovery-doc --format=rpc com.smartinteractive.blackwoods.entity.BranchEndpoint com.smartinteractive.blackwoods.PropertyEndpoint
this is the result:
V 08, 2014 9:31:11 AM com.google.apphosting.utils.config.AppEngineWebXmlReader readAppEngineWebXml
INFO: Successfully processed ./war\WEB-INF/appengine-web.xml
Error: com.smartinteractive.blackwoods.entity.BranchEndpoint
I don't have a clue what kind of error this could be. I read in this topic (App engine RPC discovery doc) that
In the Endpoint methods, the return value type cannot be simple type
such as String or int. The return value needs to be a POJO, an array
or a Collection
What else could be the problem.
BranchEndpoint:
package com.smartinteractive.blackwoods.entity;
import com.smartinteractive.blackwoods.dao.service.BranchDataService;
import com.smartinteractive.blackwoods.persistence.EMF;
import com.google.api.server.spi.config.Api;
import com.google.api.server.spi.config.ApiMethod;
import com.google.api.server.spi.config.ApiNamespace;
import com.google.api.server.spi.response.CollectionResponse;
import java.util.List;
import javax.annotation.Nullable;
import javax.inject.Named;
import javax.persistence.EntityExistsException;
import javax.persistence.EntityNotFoundException;
import javax.persistence.EntityManager;
#Api(name = "branchendpoint", namespace = #ApiNamespace(ownerDomain = "smartinteractive.com", ownerName = "smartinteractive.com", packagePath = "blackwoods.entity"))
public class BranchEndpoint {
/**
* This method lists all the entities inserted in datastore.
* It uses HTTP GET method and paging support.
*
* #return A CollectionResponse class containing the list of all entities
* persisted
*/
#SuppressWarnings("unchecked")
#ApiMethod(name = "listBranch")
public CollectionResponse<Branch> listBranch(#Nullable #Named("first") Integer first, #Nullable #Named("last") Integer last) {
EntityManager mgr = getEntityManager();
List<Branch> execute = null;
try {
if(first == null || last == null) {
execute = new BranchDataService().findWithNamedQuery(Branch.ALL);
}
else {
execute = (List<Branch>)new BranchDataService().findAllBranches(mgr, first, last, null, null, null);
}
} finally {
mgr.close();
}
return CollectionResponse.<Branch> builder().setItems(execute).build();
}
/**
* This method gets the entity having primary key id. It uses HTTP GET method.
*
* #param id the primary key of the java bean.
* #return The entity with primary key id.
*/
#ApiMethod(name = "getBranch")
public Branch getBranch(#Named("id") Integer id) {
EntityManager mgr = getEntityManager();
Branch branch = null;
try {
branch = mgr.find(Branch.class, id);
} finally {
mgr.close();
}
return branch;
}
/**
* This inserts a new entity into App Engine datastore. If the entity already
* exists in the datastore, an exception is thrown.
* It uses HTTP POST method.
*
* #param branch the entity to be inserted.
* #return The inserted entity.
*/
#ApiMethod(name = "insertBranch")
public Branch insertBranch(Branch branch) {
EntityManager mgr = getEntityManager();
try {
if (containsBranch(branch)) {
throw new EntityExistsException("Object already exists");
}
mgr.persist(branch);
} finally {
mgr.close();
}
return branch;
}
/**
* This method is used for updating an existing entity. If the entity does not
* exist in the datastore, an exception is thrown.
* It uses HTTP PUT method.
*
* #param branch the entity to be updated.
* #return The updated entity.
*/
#ApiMethod(name = "updateBranch")
public Branch updateBranch(Branch branch) {
EntityManager mgr = getEntityManager();
try {
if (!containsBranch(branch)) {
throw new EntityNotFoundException("Object does not exist");
}
mgr.persist(branch);
} finally {
mgr.close();
}
return branch;
}
private boolean containsBranch(Branch branch) {
EntityManager mgr = getEntityManager();
boolean contains = true;
try {
Branch item = mgr.find(Branch.class, branch.getId());
if (item == null) {
contains = false;
}
} finally {
mgr.close();
}
return contains;
}
private static EntityManager getEntityManager() {
return EMF.get().createEntityManager();
}
}