Do not put validation annotaiton if return type is a nullable list having non-null values

[kobylynskyi]

Discussed in #955

^{Originally posted by siva54 January 31, 2022}
Hi,
I was trying to generate the schema with a List type and came across some issues. As per the schema we have different use cases for a not-null condition for a list,

In my project, I'm using a couple of cases too such as,
[Int!] - This means that the list can be null but cannot have null objects in the list.
[Int]! - This means that the list cannot be null but can have null objects in the list.
When using codegen to generate POJOs, for types with
[Int!]
[Int]!

In both cases, the field is being annotated with,
@javax.validation.constraints.NotNull

This basically means that the List cannot be null. This is incorrect for the type [Int!] and caused some trouble. As of now, I replaced all the NotNull to instead use a PlaceboValidation annotation of mine that does nothing. How do I overcome this and make sure to ensure that the POJO created works as expected?

[kobylynskyi]

Will be released as part of version 5.4.1 #980