Consider following schema fragment:

type Mutation { deleteField(fieldId: ID!): Field! deleteFields(fieldIds: [ID!]!): [Field!]! }

On backend ID is of type Long.

Resolver methods for above mutations expect Long and List<Long> arguments:

public List<FieldDto> deleteField(Long fieldId) 

public List<FieldDto> deleteFields(List<Long> fieldIds) 

On version 5.7.1 everything works correctly.

On version 6.0.0 single ID is resolved correctly to Long, but list of ids [ID] is resolved to List<String> (instead List<Long>)

Here is a screenshot from the debugger:

• version 5.7.1 (Expected behaviour)
  

• version 6.0.0 (Incorrect behaviour)