Many of the DatastoreService methods use ClassTags, which is syntactic sugar for adding an implicit parameter. But then you can't explicitly specify any other implicit parameters such as the ExecutionContext. The problem is discussed here:
https://stackoverflow.com/questions/23718165/implicit-parameter-and-classtag
The solution is for each method to explicitly define the first implicit parameter as evidence: ClassTag[T].
Many of the DatastoreService methods use ClassTags, which is syntactic sugar for adding an implicit parameter. But then you can't explicitly specify any other implicit parameters such as the ExecutionContext. The problem is discussed here: https://stackoverflow.com/questions/23718165/implicit-parameter-and-classtag
The solution is for each method to explicitly define the first implicit parameter as
evidence: ClassTag[T].