Correct handling of null max aggregation values in SearchResponse

[kaituo]

Description

Previously, when the max aggregation in SearchResponse returned a null value, it was converted to a negative number (-9223372036854775808), leading to erroneous timestamps.

This fix adds a check to ensure that only valid positive aggregation values are considered, preventing null or invalid values from being misinterpreted as negative numbers. The change applies to only timestamps. So a positive number filter is always right.

Testing done:

1. Added unit tests to cover scenarios where max aggregation returns null or negative values, ensuring the method returns Optional.empty() when the value is invalid.
2. Added unit tests to verify correct handling of valid positive max aggregation values.
3. Ran e2e manual testing.

Previously:

POST /_plugins/_anomaly_detection/detectors/_validate/model
{
    "name": "test-detector-13",
    "description": "Test detector",
    "time_field": "customer_birth_date",
    "indices": ["opensearch_dashboards_sample_data_ecommerce"],
    "feature_attributes": [
        {
            "feature_name": "cpu",
            "feature_enabled": true,
            "aggregation_query": {
                "total_revenue_usd-field": {
                    "max": {
                        "field": "day_of_week_i"
                    }
                }
            }
        }
    ],
    "detection_interval": {
        "period": {
            "interval":1,
            "unit": "Minutes"
        }
    },
    "window_delay": {
        "period": {
            "interval": 1,
            "unit": "Minutes"
        }
    },
    "category_field": ["currency"]
}

returns:

nested: OpenSearchParseException[failed to parse date field [-9223372036854775808] with format [strict_date_optional_time||epoch_millis]: [failed to parse date field [-9223372036854775808] with format [strict_date_optional_time||epoch_millis]]]; nested: IllegalArgumentException[failed to parse date field [-9223372036854775808] with format [strict_date_optional_time||epoch_millis]]; nested: DateTimeParseException[Failed to parse with all enclosed parsers]; } opensearch-ccs-node1 | [2024-09-03T15:05:45,776][ERROR][o.o.t.r.h.ModelValidationActionHandler] [2a2cd14da04d] Failed to create search request for last data point opensearch-ccs-node1 | org.opensearch.action.search.SearchPhaseExecutionException: all shards failed opensearch-ccs-node1 | at org.opensearch.action.search.AbstractSearchAsyncAction.onPhaseFailure(AbstractSearchAsyncAction.java:770) [opensearch-3.0.0.jar:3.0.0]

Now the call returns:

{ "model": { "time_field": { "message": "There isn't enough historical data found with current timefield selected." } } }

Check List

• New functionality includes testing.
• New functionality has been documented.
• API changes companion pull request created.
• Commits are signed per the DCO using --signoff.
• Public documentation issue/PR created.

By submitting this pull request, I confirm that my contribution is made under the terms of the Apache 2.0 license.
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[codecov]

Codecov Report

Attention: Patch coverage is 50.00000% with 1 line in your changes missing coverage. Please review.

Project coverage is 77.48%. Comparing base (3f0fc8c) to head (8b49399).
Report is 10 commits behind head on main.

Files with missing lines	Patch %	Lines
...ava/org/opensearch/timeseries/util/ParseUtils.java	50.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff              @@
##               main    #1292      +/-   ##
============================================
+ Coverage     71.83%   77.48%   +5.65%     
- Complexity     4898     5422     +524     
============================================
  Files           518      532      +14     
  Lines         22879    23264     +385     
  Branches       2245     2305      +60     
============================================
+ Hits          16434    18025    +1591     
+ Misses         5410     4180    -1230     
- Partials       1035     1059      +24     

Flag	Coverage Δ
plugin	77.48% <50.00%> (+5.65%)	⬆️

Flags with carried forward coverage won't be shown. Click here to find out more.

Files with missing lines	Coverage Δ
...ava/org/opensearch/timeseries/util/ParseUtils.java	78.69% <50.00%> (+1.48%)	⬆️

... and 106 files with indirect coverage changes