[2.4.1] input null on collection will get a error graphql query

[jxnu-liguobin]

Issue Description

Hi, i find a minor question in query string (maybe)
Describe your bug in detail.

Steps to Reproduce

invoke:

jobMutationService.submitSegmentUserExportJob("ExQWkgQ7", null, null, charset = "UTF-16LE")

query:

{"query":"mutation { submitSegmentUserExportJob(segmentId: \"ExQWkgQ7\", , , charset: \"UTF-16LE\"){ name error { code message __typename } id updater creator description stage creatorId createdAt updaterId updatedAt __typename } }"}

if use Collections.emptyList()

jobMutationService.submitSegmentUserExportJob("ExQWkgQ7", Collections.emptyList(), Collections.emptyList(), charset = "UTF-16LE")

query is

{"query":"mutation { submitSegmentUserExportJob(segmentId: \"ExQWkgQ7\", tags: [  ], properties: [  ], charset: \"UTF-16LE\"){ name error { code message __typename } id __typename stage description creatorId createdAt updaterId updatedAt creator updater } }"}

Expected Result

Explain in detail what behavior you expected to happen.

my schema:

submitSegmentUserExportJob(segmentId: HashId!, tags: [HashId!], properties: [String!], charset: String): SegmentUserExportJob!

In Java, collection is allowed to be given null. As a non mandatory field, can I use null or not?
I want there will be no extra commas like code blocksegmentId: \"ExQWkgQ7\", , , charset:
Of course, I'm not sure if there will be any other problems at the moment. I think it is probably the best to support option

Actual Result

Explain in detail what behavior actually happened.

Your Environment and Setup

• graphql-java-codegen: E.g.: 2.4.1
• Build tool: E.g.: Maven
• Java tool: E.g.: Oracle 8u241
• Mapping Config: E.g.:

<configuration>
    <outputDir>${project.build.directory}/generated-sources/graphql</outputDir>
    <packageName>io.github.kobylynskyi.graphql.model</packageName>
</configuration>

Additional context

Add any other context about the problem here.

[kobylynskyi]

This fixed was released in version 3.0.0 today