Getting incorrect return from get_commit_diffs()

[meAbab]

I'm trying to get the diff between two commit, therefore using this API as,

            ref_heads = git_client.get_refs(repository_id=REPOSITORY_ID, project=PROJECT_NAME, filter=target_branch)
            master_commit_id = ref_heads.value[0].object_id
            source_commit_id = pull_request.last_merge_source_commit.commit_id

            base_version_descriptor = GitBaseVersionDescriptor(version_type='commit', version=master_commit_id)
            target_version_descriptor = GitTargetVersionDescriptor(version_type='commit', version=source_commit_id)

            commit_diffs = git_client.get_commit_diffs(repository_id=REPOSITORY_ID, project=PROJECT_NAME,
                                                       diff_common_commit=True,
                                                        base_version_descriptor=base_version_descriptor,
                                                        target_version_descriptor=target_version_descriptor)

while print the commit_diffs, having output as,

Diffs Response: {'additional_properties': {}, 'ahead_count': 0, 'all_changes_included': True, 'base_commit': 'b106b44eebeef93d5240f08dca8ceb0124ca4415', 'behind_count': 0, 'change_counts': {}, 'changes': [], 'common_commit': 'b106b44eebeef93d5240f08dca8ceb0124ca4415', 'target_commit': 'b106b44eebeef93d5240f08dca8ceb0124ca4415'}

whereas, using curl to set direct REST request, returns correct output.

"https://dev.azure.com/ORGANIZATION/project/_apis/git/repositories/a21206d3-9bdb-41c4-8b77-56f82360a311e/diffs/commits?baseVersionType=commit&baseVersion=b106b44eebeef93d5240f08dca8ceb0124ca4415&targetVersionType=commit&targetVersion=165c197e54d689e9910eb111b9c14e2516184dd8&api-version=6.0"

What is the correct way to use the get_commit_diff()? Or what I'm doing wrong?