update version checks in ElasticsearchException serialization code

5.3.0 is the first version that contains the split from headers to metadata, updated the check to reflect that. It was previously after to be able to commit to master first, and only after that backport the change. Otherwise master tests would have failed until the change was backported.

Author: javanna

core/src/main/java/org/elasticsearch/ElasticsearchException.java

@@ -131,8 +131,7 @@ public ElasticsearchException(StreamInput in) throws IOException {
         super(in.readOptionalString(), in.readException());
         readStackTrace(this, in);
         headers.putAll(in.readMapOfLists(StreamInput::readString, StreamInput::readString));
-        //TODO change to onOrAfter once backported to 5.x
-        if (in.getVersion().after(Version.V_5_3_0_UNRELEASED)) {
+        if (in.getVersion().onOrAfter(Version.V_5_3_0_UNRELEASED)) {
             metadata.putAll(in.readMapOfLists(StreamInput::readString, StreamInput::readString));
         } else {
             for (Iterator<Map.Entry<String, List<String>>> iterator = headers.entrySet().iterator(); iterator.hasNext(); ) {
@@ -283,8 +282,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeOptionalString(this.getMessage());
         out.writeException(this.getCause());
         writeStackTraces(this, out);
-        //TODO change to onOrAfter once backported to 5.x
-        if (out.getVersion().after(Version.V_5_3_0_UNRELEASED)) {
+        if (out.getVersion().onOrAfter(Version.V_5_3_0_UNRELEASED)) {
             out.writeMapOfLists(headers, StreamOutput::writeString, StreamOutput::writeString);
             out.writeMapOfLists(metadata, StreamOutput::writeString, StreamOutput::writeString);
         } else {