Enable bwc tests now that #38443 is backported. (#38462)

build.gradle

@@ -159,8 +159,8 @@ task verifyVersions {
  * the enabled state of every bwc task. It should be set back to true
  * after the backport of the backcompat code is complete.
  */
-final boolean bwc_tests_enabled = false
-final String bwc_tests_disabled_issue = "https://github.com/elastic/elasticsearch/pull/38443" /* place a PR link here when committing bwc changes */
+final 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")

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ccr/action/PutAutoFollowPatternAction.java

@@ -153,7 +153,7 @@ public Request(StreamInput in) throws IOException {
             remoteCluster = in.readString();
             leaderIndexPatterns = in.readStringList();
             followIndexNamePattern = in.readOptionalString();
-            if (in.getVersion().onOrAfter(Version.V_7_0_0)) {
+            if (in.getVersion().onOrAfter(Version.V_6_7_0)) {
                 parameters = new FollowParameters(in);
             } else {
                 parameters = new FollowParameters();
@@ -177,7 +177,7 @@ public void writeTo(StreamOutput out) throws IOException {
             out.writeString(remoteCluster);
             out.writeStringCollection(leaderIndexPatterns);
             out.writeOptionalString(followIndexNamePattern);
-            if (out.getVersion().onOrAfter(Version.V_7_0_0)) {
+            if (out.getVersion().onOrAfter(Version.V_6_7_0)) {
                 parameters.writeTo(out);
             } else {
                 out.writeOptionalVInt(parameters.maxReadRequestOperationCount);