SearchbackpressureStatsCollector Constants Added

[CoderJeffrey]

Signed-off-by: Jeffrey Liu [email protected]

Is your feature request related to a problem? Please provide an existing Issue # , or describe.
The SearchBackpressureStatsCollector.java added in pull & request (opensearch-project/performance-analyzer#483) use literal String value (e.g. "searchbp_nodeid"0 for json field, which is not aligned with instance accessing and coding styles with other collectors.

Describe the solution you are proposing
Added all required Constants needed by SearchbackPressureStatsCollector.java to populate the jsonFields

Example:
@JsonProperty("searchbp_nodeid") public String getSearchBackPressureStats_NodeId() { return this.nodeId; }

Has changed to:
@JsonProperty(SearchBackPressureStatsValue.Constants.SEARCHBP_NODEID) public String getSearchBackPressureStats_NodeId() { return this.nodeId; }

Describe alternatives you've considered
N/A

Additional context
Parallel Pull & Request with opensearch-project/performance-analyzer#483
This Commons Package PR (SearchbackpressureStatsCollector Constants Added #33 ) is needed in order to run the parallel PA-plugin PR.

Check List

• New functionality includes testing.
• All tests pass
• New functionality has been documented.
• New functionality has javadoc added
• Commits are signed per the DCO using --signoff

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