fix(change-summary): minor issues (#20095)

- deep copy previous change summary so that it doesnt get modified
- handle multiple fields during consolidation

openmetadata-service/src/main/java/org/openmetadata/service/jdbi3/ChangeSummarizer.java

@@ -56,7 +56,10 @@ public class ChangeSummarizer<T extends EntityInterface> {
                     new ChangeSummary()
                         .withChangeSource(changeSource)
                         .withChangedAt(changedAt)
-                        .withChangedBy(changedBy)));
+                        .withChangedBy(changedBy),
+                // If its a consolidation, we might have multiple changes for the same field.
+                // Since we are only interested in the field name, we can just take whichever.
+                (existing, replacement) -> existing));
   }
 
   private boolean isFieldTracked(String fieldName) {

openmetadata-service/src/main/java/org/openmetadata/service/jdbi3/EntityRepository.java

@@ -2993,6 +2993,7 @@ public abstract class EntityRepository<T extends EntityInterface> {
       ChangeSummaryMap current =
           Optional.ofNullable(original.getChangeDescription())
               .map(ChangeDescription::getChangeSummary)
+              .map(changeSummaryMap -> JsonUtils.deepCopy(changeSummaryMap, ChangeSummaryMap.class))
               .orElse(new ChangeSummaryMap());
 
       Map<String, ChangeSummary> addedSummaries =

openmetadata-service/src/test/java/org/openmetadata/service/jdbi3/ChangeSummarizerTest.java

@@ -42,6 +42,26 @@ public class ChangeSummarizerTest {
     assert result.size() == 0;
   }
 
+  @Test
+  public void test_duplicateEntriesConsolidation() {
+    String fieldName = "description";
+    ChangeSource changeSource = ChangeSource.MANUAL;
+    long updatedAt = System.currentTimeMillis();
+    String updatedBy = "testUser";
+    List<FieldChange> changes =
+        List.of(new FieldChange().withName(fieldName), new FieldChange().withName(fieldName));
+
+    Map<String, ChangeSummary> result =
+        changeSummarizer.summarizeChanges(Map.of(), changes, changeSource, updatedBy, updatedAt);
+    assert result.size() == 1;
+    Assertions.assertTrue(result.containsKey(fieldName));
+
+    result =
+        changeSummarizer.summarizeChanges(
+            result, changes, ChangeSource.AUTOMATED, "older-change", updatedAt - 100);
+    assert result.size() == 0;
+  }
+
   @Test
   public void test_columnDescription() {
     String fieldName = "columns.column1.description";