TypeMappingException: Multiple methods detected for operation "opName" with different return types

Question

Working with graphql-spqr and Spring Boot, I'm trying to run the project but I run into this:

exception:org.springframework.beans.factory.BeanCreationException: Error creating bean
with name 'graphQLSchema' defined in class path resource 
[io/leangen/graphql/spqr/spring/autoconfigure/SpqrAutoConfiguration.class]: 
Bean instantiation via factory method failed; 
nested exception is org.springframework.beans.BeanInstantiationException: Failed to instantiate 
[graphql.schema.GraphQLSchema]: Factory method 'graphQLSchema' threw exception; 
nested exception is io.leangen.graphql.metadata.exceptions.TypeMappingException: 
Multiple methods detected  for operation "defaultInstanceForType" with different 
return types. Types found: [com.google.protobuf.Message, com.google.protobuf.MessageLite]. 
If this is intentional, and you wish GraphQL SPQR to infer the most common super type automatically, see 
https://github.com/leangen/graphql-spqr/wiki/Errors#operation-with-multiple-resolver-methods-of-different-types 

and I got redirected to this for help : https://github.com/leangen/graphql-spqr/wiki/Errors#operation-with-multiple-resolver-methods-of-different-types

I was not having multiple methods with the same name which triggers me, the URL in the exception is not helpful and can't even be edited or commented.

Answer 1

Removing the protobuf Timestamp fields fix the problem!

After changing my return Object it worked out, I had to refactor com.google.protobuf.Timestamp to Date, LocalDate or even String and it works perfectly.