Restore and update java examples

[l-trotta]

Java examples have been accidentally removed from the language example files.
File was accidentally removed: #5265
Then restored, but without java examples: #5281
Restoring the java examples and updating them using the 9.2 client.

[github-actions]

Following you can find the validation changes against the target branch for the APIs.

API	Status	Request	Response
bulk	🟢	548/548 → 558/558	566/566 → 576/576
indices.create_data_stream	🟢	121/121 → 131/131	121/121 → 131/131
indices.delete_data_stream	🟢	96/96 → 98/98	96/96 → 98/98
indices.get_sample	🔴	13/13 → 24/24	9/13 → 16/24
indices.get_sample_stats	🔴	14/14 → 26/26	13/14 → 24/26
indices.put_index_template	🔴	130/154 → 140/164	154/154 → 164/164
indices.rollover	🔴	59/59 → 69/69	2/59 → 2/69
search	🔴	2594/2615 → 2593/2612	2615/2615 → 2612/2612

You can validate these APIs yourself by using the make validate target.

[pquentin]

Thanks! LGTM.