Fix non-deterministic field ordering in AnnotationSourceTSV annotation extraction

[Copilot]

AnnotationSourceTSV was iterating over HashMap.keySet() to build the precomputed fieldNames/fieldPositions arrays, producing annotation output in arbitrary order rather than the user-requested field order.

Changes

• AnnotationSourceTSV.java: Replace keyset iteration with fieldNames.split(",") when building precomputed arrays. The HashMap is retained for O(1) position lookups; only the iteration source changes.

// Before — non-deterministic HashMap keyset order
this.fieldNames = headerNameAndPosition.keySet().toArray(new String[0]);
this.fieldPositions = new int[this.fieldNames.length];
for (int i = 0; i < this.fieldNames.length; i++) {
    this.fieldPositions[i] = headerNameAndPosition.get(this.fieldNames[i]);
}

// After — preserves user-requested field order
String[] requestedFields = fieldNames.split(",");
this.fieldNames = requestedFields;
this.fieldPositions = new int[requestedFields.length];
for (int i = 0; i < requestedFields.length; i++) {
    this.fieldPositions[i] = headerNameAndPosition.get(requestedFields[i]);
}

Since getHeaderNameAndPositions also splits on "," to build the map, the keys are guaranteed to match — no risk of NullPointerException at lookup time.

Type of change

• Bug fix (non-breaking change which fixes an issue)

How Has This Been Tested?

• Existing AnnotationSourceTSVTest unit tests cover extractFieldsFromRecord and getHeaderNameAndPositions

Are WDL Updates Required?

No WDL changes required.

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

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