Liferay Service Builder创建重复的方法

Question

在我的service.xml我定义了两个实体Assignment和Submission，后者包含<column name="assignmentId" type="long"></column>。

运行Gradle buildService后，我在AssignmentLocalService中收到了此代码：

public Assignment addAssignment(Assignment assignment);

[...]

@Indexable(type = IndexableType.REINDEX)
    public Assignment addAssignment(Assignment assignment);

Eclipse将此标记为错误，Gradle的jar任务失败并显示：

error: method addAssignment(Assignment) is already defined in interface AssignmentLocalService

为什么Service Builder会这样做？
如何防止它创建重复的方法，或者如果Service Builder实际上正在做正确的事情，如何使编译工作？