Ignore isJoda flag from 7x nodes (#53481)

when upgrading from 7.7+ ES will send out a flag indicating if a pattern is of joda style. This is only used to support joda style indices in 7.x, in 8 we no longer support this. All indices in 8 should use java style pattern. Hence we can ignore this flag. Similarly when writing from v8 to v7.7+ we should always send false flag.

relates #52555
relates #53478
closes #53477

Author: pgomulka

build.gradle

@@ -221,8 +221,8 @@ task verifyVersions {
  * after the backport of the backcompat code is complete.
  */
 
-boolean bwc_tests_enabled = false
-final String bwc_tests_disabled_issue = "https://github.com/elastic/elasticsearch/issues/53477" /* place a PR link here when committing bwc changes */
+boolean bwc_tests_enabled = true
+final String bwc_tests_disabled_issue = "" /* place a PR link here when committing bwc changes */
 if (bwc_tests_enabled == false) {
   if (bwc_tests_disabled_issue.isEmpty()) {
     throw new GradleException("bwc_tests_disabled_issue must be set when bwc_tests_enabled == false")

server/src/main/java/org/elasticsearch/search/DocValueFormat.java

@@ -21,6 +21,7 @@
 
 import org.apache.lucene.document.InetAddressPoint;
 import org.apache.lucene.util.BytesRef;
+import org.elasticsearch.Version;
 import org.elasticsearch.common.io.stream.NamedWriteable;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
@@ -201,6 +202,13 @@ public DateTime(StreamInput in) throws IOException {
             String zoneId = in.readString();
             this.timeZone = ZoneId.of(zoneId);
             this.resolution = DateFieldMapper.Resolution.ofOrdinal(in.readVInt());
+            if (in.getVersion().onOrAfter(Version.V_7_7_0) && in.getVersion().before(Version.V_8_0_0)) {
+                /* when deserialising from 7.7+ nodes expect a flag indicating if a pattern is of joda style
+                   This is only used to support joda style indices in 7.x, in 8 we no longer support this.
+                   All indices in 8 should use java style pattern. Hence we can ignore this flag.
+                */
+                in.readBoolean();
+            }
         }
 
         @Override
@@ -213,6 +221,13 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeString(formatter.pattern());
             out.writeString(timeZone.getId());
             out.writeVInt(resolution.ordinal());
+            if (out.getVersion().onOrAfter(Version.V_7_7_0) && out.getVersion().before(Version.V_8_0_0)) {
+                /* when serializing to 7.7+  send out a flag indicating if a pattern is of joda style
+                   This is only used to support joda style indices in 7.x, in 8 we no longer support this.
+                   All indices in 8 should use java style pattern. Hence this flag is always false.
+                */
+                out.writeBoolean(false);
+            }
         }
 
         @Override