GoogleCredential credential = new GoogleCredential.Builder().setTransport(
new NetHttpTransport()).setJsonFactory(new JacksonFactory()).build();
credential.setAccessToken("TEST_ACCESS_TOKEN");
DfpSession session = new DfpSession.Builder().withApplicationName("TEST_APP")
.withOAuth2Credential(credential)
.withEndpoint(testHttpServer.getServerUrl())
.withNetworkCode("TEST_NETWORK_CODE")
.build();