Java Play 2.8 + GraphQL

如何解决Java Play 2.8 + GraphQL

我正在尝试将GraphQL添加到我的Play服务中。 每次更新文件时，SBT都会重新加载项目，但是，一旦重新加载项目，GraphQL就会停止工作。 从错误中，我可以推断出问题在于调用POJO中的get方法。 但是我不确定为什么它无法在POJO中找到get方法

n.g.e.SimpleDataFetcherExceptionHandler - Exception while fetching data (/country/id) : object is not an instance of declaring class
java.lang.IllegalArgumentException: object is not an instance of declaring class
    at sun.reflect.NativeMethodAccessorImpl.invoke0(Native Method)
    at sun.reflect.NativeMethodAccessorImpl.invoke(NativeMethodAccessorImpl.java:62)
    at sun.reflect.DelegatingMethodAccessorImpl.invoke(DelegatingMethodAccessorImpl.java:43)
    at java.lang.reflect.Method.invoke(Method.java:498)
    at graphql.schema.PropertyDataFetcherHelper.getPropertyViaGetterUsingPrefix(PropertyDataFetcherHelper.java:108)
    at graphql.schema.PropertyDataFetcherHelper.getPropertyViaGetterMethod(PropertyDataFetcherHelper.java:94)
    at graphql.schema.PropertyDataFetcherHelper.getPropertyValue(PropertyDataFetcherHelper.java:53)
    at graphql.schema.PropertyDataFetcher.get(PropertyDataFetcher.java:120)
    at graphql.execution.ExecutionStrategy.fetchField(ExecutionStrategy.java:272)
    at graphql.execution.ExecutionStrategy.resolveFieldWithInfo(ExecutionStrategy.java:200)

任何想法都会受到赞赏。