[ML] Fix ZeroShotClassificationConfig update mixing labels (#82848)

Author: davidkyle

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/ZeroShotClassificationConfigUpdate.java

@@ -152,7 +152,7 @@ public InferenceConfig apply(InferenceConfig originalConfig) {
     }
 
     boolean isNoop(ZeroShotClassificationConfig originalConfig) {
-        return (labels == null || labels.equals(originalConfig.getClassificationLabels()))
+        return (labels == null || labels.equals(originalConfig.getLabels()))
             && (isMultiLabel == null || isMultiLabel.equals(originalConfig.isMultiLabel()))
             && (resultsField == null || resultsField.equals(originalConfig.getResultsField()))
             && super.isNoop();

x-pack/plugin/core/src/test/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/ZeroShotClassificationConfigUpdateTests.java

@@ -178,6 +178,30 @@ public void testApplyWithEmptyLabelsInConfigAndUpdate() {
 
     public void testIsNoop() {
         assertTrue(new ZeroShotClassificationConfigUpdate.Builder().build().isNoop(ZeroShotClassificationConfigTests.createRandom()));
+
+        var originalConfig = new ZeroShotClassificationConfig(
+            List.of("contradiction", "neutral", "entailment"),
+            randomBoolean() ? null : VocabularyConfigTests.createRandom(),
+            randomBoolean() ? null : BertTokenizationTests.createRandom(),
+            randomAlphaOfLength(10),
+            randomBoolean(),
+            null,
+            randomBoolean() ? null : randomAlphaOfLength(8)
+        );
+
+        var update = new ZeroShotClassificationConfigUpdate.Builder().setLabels(List.of("glad", "sad", "mad")).build();
+        assertFalse(update.isNoop(originalConfig));
+
+        originalConfig = new ZeroShotClassificationConfig(
+            List.of("contradiction", "neutral", "entailment"),
+            randomBoolean() ? null : VocabularyConfigTests.createRandom(),
+            randomBoolean() ? null : BertTokenizationTests.createRandom(),
+            randomAlphaOfLength(10),
+            randomBoolean(),
+            List.of("glad", "sad", "mad"),
+            randomBoolean() ? null : randomAlphaOfLength(8)
+        );
+        assertTrue(update.isNoop(originalConfig));
     }
 
     public static ZeroShotClassificationConfigUpdate createRandom() {