ingest: date processor should not fail if timestamp is specified as json number

Closes #26967

Author: martijnvg

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DateIndexNameProcessor.java

@@ -63,7 +63,12 @@ public final class DateIndexNameProcessor extends AbstractProcessor {
     @Override
     public void execute(IngestDocument ingestDocument) throws Exception {
         // Date can be specified as a string or long:
-        String date = Objects.toString(ingestDocument.getFieldValue(field, Object.class));
+        Object obj = ingestDocument.getFieldValue(field, Object.class);
+        String date = null;
+        if (obj != null) {
+            // Not use Objects.toString(...) here, because null gets changed to "null" which may confuse some date parsers
+            date = obj.toString();
+        }
 
         DateTime dateTime = null;
         Exception lastException = null;

modules/ingest-common/src/main/java/org/elasticsearch/ingest/common/DateProcessor.java

@@ -29,10 +29,10 @@
 import org.joda.time.format.ISODateTimeFormat;
 
 import java.util.ArrayList;
-import java.util.IllformedLocaleException;
 import java.util.List;
 import java.util.Locale;
 import java.util.Map;
+import java.util.Objects;
 import java.util.function.Function;
 
 public final class DateProcessor extends AbstractProcessor {
@@ -63,7 +63,12 @@ public final class DateProcessor extends AbstractProcessor {
 
     @Override
     public void execute(IngestDocument ingestDocument) {
-        String value = ingestDocument.getFieldValue(field, String.class);
+        Object obj = ingestDocument.getFieldValue(field, Object.class);
+        String value = null;
+        if (obj != null) {
+            // Not use Objects.toString(...) here, because null gets changed to "null" which may confuse some date parsers
+            value = obj.toString();
+        }
 
         DateTime dateTime = null;
         Exception lastException = null;

modules/ingest-common/src/test/java/org/elasticsearch/ingest/common/DateProcessorTests.java

@@ -134,6 +134,12 @@ public void testUnixMs() {
         IngestDocument ingestDocument = RandomDocumentPicks.randomIngestDocument(random(), document);
         dateProcessor.execute(ingestDocument);
         assertThat(ingestDocument.getFieldValue("date_as_date", String.class), equalTo("1970-01-01T00:16:40.500Z"));
+
+        document = new HashMap<>();
+        document.put("date_as_string", 1000500L);
+        ingestDocument = RandomDocumentPicks.randomIngestDocument(random(), document);
+        dateProcessor.execute(ingestDocument);
+        assertThat(ingestDocument.getFieldValue("date_as_date", String.class), equalTo("1970-01-01T00:16:40.500Z"));
     }
 
     public void testUnix() {