TranslationContextData is used internally by SetWindowFields, but had to be made public because it was needed in the public method signature of ExpressionAggregationExpressionDefinition. This led to API docs warnings because TranslationContextData resides in an internal LINQ3 namespace. Rather than expose this internal namespace, overload the ExpressionAggregationExpressionDefinition with an internal ctor that takes TranslationContextData and make TranslationContextData internal.