title: 'ENDPOINTS_SERVICE_NAME' is not set on Cloud Endpoints with Firebase auth
body: <p>When I call my API as:</p>
  
  <blockquote>
    <p>PUT <a href="https://[Project-id].appspot.com/_ah/api/person/v2/[id]/thanks?thanks=true" rel="nofollow noreferrer">https://[Project-id].appspot.com/_ah/api/person/v2/[id]/thanks?thanks=true</a></p>
  </blockquote>
  
  <p>The response is a <strong>400 BadRequest</strong>. </p>
  
  <pre><code>{
   "error": {
      "errors": [
          {
          "domain": "global",
          "reason": "badRequest",
          "message": "java.lang.IllegalArgumentException: Environment variable 'ENDPOINTS_SERVICE_NAME' is not set"
          }
       ],
       "code": 400,
       "message": "java.lang.IllegalArgumentException: Environment variable 'ENDPOINTS_SERVICE_NAME' is not set"
    }
  }
  </code></pre>
  
  <p>The response should be <strong>401 Unauthorized</strong>, because i use Authentification with Firebase.</p>
  
  <p>The Api definition:</p>
  
  <pre><code> @Api(
      name = "person",
      version="v2",
      authenticators = {EspAuthenticator.class},
      issuers = {
              @ApiIssuer(
                      name = "firebase",
                      issuer = "https://securetoken.google.com/[Project-id] ",
                      jwksUri = "https://www.googleapis.com/service_accounts/v1/metadata/x509/securetoken@system.gserviceaccount.com")
      },
      issuerAudiences = {
              @ApiIssuerAudience(name = "firebase", audiences = "[Project-id] ")
      }
      )
  </code></pre>
  
  <p>And the Api method:</p>
  
  <pre><code>@ApiMethod(name = "thanks",path = "{personId}/thanks",httpMethod = ApiMethod.HttpMethod.PUT)
  public Object thanks(@Named("personId") String personId, @Named("thanks") Boolean thanks, User user) throws IOException, NotFoundException, UnauthorizedException {
      if (user == null) {
          throw new UnauthorizedException("Invalid credentials");
      }
  
      MyBean ty= new MyBean(thanks);
      return ty;
  
  }
  </code></pre>