使用Java插入webProperty'；s"；谷歌API客户端库“；

我正在尝试使用Java客户端创建webProperty，但没有成功（我可以访问允许创建webProperties的beta测试组）。这是我的代码（它实际上是一个groovy类）：

这是一个Spring服务，当创建这个对象时，我没有得到任何异常。问题是，当尝试调用insertWebProperty方法时，我得到以下结果：

java.lang.NullPointerException: null
 at com.google.api.client.json.webtoken.JsonWebSignature.signUsingRsaSha256(JsonWebSignature.java:498) ~[google-http-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.executeRefreshToken(GoogleCredential.java:378) ~[google-api-client-1.19.0.jar:1.19.0]
 at com.google.api.client.auth.oauth2.Credential.refreshToken(Credential.java:489) ~[google-oauth-client-1.19.0.jar:1.19.0]
 at com.google.api.client.auth.oauth2.Credential.intercept(Credential.java:217) ~[google-oauth-client-1.19.0.jar:1.19.0]
 at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:859) ~[google-http-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:410) ~[google-api-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:343) ~[google-api-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:460) ~[google-api-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.services.AbstractGoogleClientRequest$execute.call(Unknown Source) ~[na:na]

有人知道吗？？提前谢谢

java.lang.NullPointerException: null
 at com.google.api.client.json.webtoken.JsonWebSignature.signUsingRsaSha256(JsonWebSignature.java:498) ~[google-http-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.auth.oauth2.GoogleCredential.executeRefreshToken(GoogleCredential.java:378) ~[google-api-client-1.19.0.jar:1.19.0]
 at com.google.api.client.auth.oauth2.Credential.refreshToken(Credential.java:489) ~[google-oauth-client-1.19.0.jar:1.19.0]
 at com.google.api.client.auth.oauth2.Credential.intercept(Credential.java:217) ~[google-oauth-client-1.19.0.jar:1.19.0]
 at com.google.api.client.http.HttpRequest.execute(HttpRequest.java:859) ~[google-http-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:410) ~[google-api-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.executeUnparsed(AbstractGoogleClientRequest.java:343) ~[google-api-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.services.AbstractGoogleClientRequest.execute(AbstractGoogleClientRequest.java:460) ~[google-api-client-1.19.0.jar:1.19.0]
 at com.google.api.client.googleapis.services.AbstractGoogleClientRequest$execute.call(Unknown Source) ~[na:na]