title: Google API identify toolkit returning configuration_not_found
body: <p>While trying to login to a Firebase account using a custom token, this error shows. 
  what would be the cause of the error?</p>
  
  <pre><code>07-25 15:04:16.523  2357   811 E Volley  : [448] BasicNetwork.performRequest: Unexpected response code 400 for https://www.googleapis.com/identitytoolkit/v3/relyingparty/verifyCustomToken?key={TOKEN_CODE}
  07-25 15:04:16.524  2357  2530 I AuthChimeraService: Error description received from server: {
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:  "error": {
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:   "errors": [
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:    {
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:     "domain": "global",
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:     "reason": "invalid",
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:     "message": "CONFIGURATION_NOT_FOUND"
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:    }
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:   ],
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:   "code": 400,
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:   "message": "CONFIGURATION_NOT_FOUND"
  07-25 15:04:16.524  2357  2530 I AuthChimeraService:  }
  07-25 15:04:16.524  2357  2530 I AuthChimeraService: }
  07-25 15:04:16.524  2357  2530 D AuthIntentChimeraService: Finished operation: &lt;&lt; dms (350ms elapsed)
  </code></pre>
  
  <p>My current code</p>
  
  <pre><code>mAuth = FirebaseAuth.getInstance();
          mAuth.signInWithCustomToken(mCustomToken)
                  .addOnCompleteListener(this, new OnCompleteListener&lt;AuthResult&gt;() {
                      @Override
                      public void onComplete(@NonNull Task&lt;AuthResult&gt; task) {
                          Log.d("d", "signInWithCustomToken:onComplete:" + task.isSuccessful());
  
                          if (!task.isSuccessful()) {
                              Log.w("d", "signInWithCustomToken", task.getException());
                              Toast.makeText(MainActivity.this, "Authentication failed.",
                                      Toast.LENGTH_SHORT).show();
                          }
                      }
                  });
  </code></pre>