HDDS-5306. Add ozone sh * getacl option to match setacl input format

[echonesis]

What changes were proposed in this pull request?

Enhanced the ozone sh bucket|key|volume getacl command to support a --json flag.
The command now outputs JSON format by default (consistent with other Ozone CLI commands).
Users can use --json=false to get a comma-separated string format compatible with setacl/addacl commands.

What is the link to the Apache JIRA

https://issues.apache.org/jira/browse/HDDS-5306

How was this patch tested?

GitHub Actions CI: https://github.com/echonesis/ozone/actions/runs/20594091686
Local Test:

> docker compose exec om ozone sh bucket getacl s3v/bucket1
[ {
  "type" : "USER",
  "name" : "testuser",
  "aclScope" : "ACCESS",
  "aclSet" : [ "ALL" ],
  "aclList" : [ "ALL" ]
}, {
  "type" : "GROUP",
  "name" : "testuser",
  "aclScope" : "ACCESS",
  "aclSet" : [ "READ", "LIST" ],
  "aclList" : [ "READ", "LIST" ]
} ]

> docker compose exec om ozone sh bucket getacl --json s3v/bucket1
[ {
  "type" : "USER",
  "name" : "testuser",
  "aclScope" : "ACCESS",
  "aclList" : [ "ALL" ],
  "aclSet" : [ "ALL" ]
}, {
  "type" : "GROUP",
  "name" : "testuser",
  "aclScope" : "ACCESS",
  "aclList" : [ "READ", "LIST" ],
  "aclSet" : [ "READ", "LIST" ]
} ]

> docker compose exec om ozone sh bucket getacl --json=false s3v/bucket1
user:testuser:a,group:testuser:rl

[ChenSammi]

Thanks @echonesis for working on this task.

I would suggest add an following Option instead of this one,

  @CommandLine.Option(names = {"--json"},
      description = "Format output as JSON",
      defaultValue = "true")
  private boolean json;

The rest looks good to me.

[echonesis]

Thank you for the review!
I've been considering the --json approach with the following concerns:

1. Clearer user intent: The --string flag explicitly opts into the string format, while --json with defaultValue="true" creates confusion (why have a flag for the default behavior?).
2. Backward compatibility: The current implementation maintains the existing default JSON output without any flags, which is less disruptive to existing users.
3. Future extensibility: If we need additional formats (e.g., --xml or --yaml), having explicit format flags is cleaner than having --json=false alongside other format flags.

What do you think? I'm open to your perspective on this!

[ChenSammi]

It's very good to thought that there are possible other formats to support in future. But the current Ozone CLI state is either json or plain output without structured format, so --json is used in many CLIs. To have a consistent CLI option format, --json is preferred. There is possibility to support xml or yaml in future, but we don't see such requirements so far. If it becomes true, then a lot of existing CLIs need to improved in batches.

why have a flag for the default behavior?

If there is --json in the command line, then it's true, otherwise it's false. So default "true" might not be feasible, "false" is more appropriate.

"--string", "-o"

"--string" is kind of vague, user cannot get the clear idea about what this option means without looking into description, and "-o" usually means "--output-file". A self explained option name is more preferred.

[ChenSammi]

I guess(didn't test it) defaultValue = "true" will cause problem, there could be no way to get a false state, could you test it if defaultValue = "true" works? The reason why defaultValue = "true" is recommended at first place is to keep the backward compatibility, but if it's not feasible, I think defaultValue = "false" is acceptable, though it will change the current output behavior, but just format, not content.

[echonesis]

I've updated the Option settings, and it works for backward compatibility.

• default: JSON
• with --json: JSON
• with --json=false: String

We could use the syntax:

@Option(names = {"--json"},
    description = "Format output as JSON",
    defaultValue = "true",
    fallbackValue = "true")
private boolean json;

[ChenSammi]

Let's add more explanation in description.

Format output as JSON. Default is true. Use --json=false to turn off output JSON format.