Reenable bw tests after merging #50333. (#50746)

PR #50333 has been merged.

Author: jpountz

build.gradle

@@ -205,8 +205,8 @@ 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/pull/50333" /* 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")

rest-api-spec/src/main/resources/rest-api-spec/test/field_caps/20_meta.yml

@@ -2,7 +2,7 @@
 "Merge metadata across multiple indices":
 
   - skip:
-      version: " - 7.99.99"
+      version: " - 7.5.99"
       reason: Metadata support was added in 7.6
 
   - do:

rest-api-spec/src/main/resources/rest-api-spec/test/indices.put_mapping/10_basic.yml

@@ -113,7 +113,7 @@
 "Update per-field metadata":
 
   - skip:
-      version:     " - 7.99.99"
+      version:     " - 7.5.99"
       reason:      "Per-field meta was introduced in 7.6"
 
   - do:

server/src/main/java/org/elasticsearch/action/fieldcaps/FieldCapabilities.java

@@ -125,7 +125,7 @@ public FieldCapabilities(StreamInput in) throws IOException {
         this.indices = in.readOptionalStringArray();
         this.nonSearchableIndices = in.readOptionalStringArray();
         this.nonAggregatableIndices = in.readOptionalStringArray();
-        if (in.getVersion().onOrAfter(Version.V_8_0_0)) {
+        if (in.getVersion().onOrAfter(Version.V_7_6_0)) {
             meta = in.readMap(StreamInput::readString, i -> i.readSet(StreamInput::readString));
         } else {
             meta = Collections.emptyMap();
@@ -141,7 +141,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeOptionalStringArray(indices);
         out.writeOptionalStringArray(nonSearchableIndices);
         out.writeOptionalStringArray(nonAggregatableIndices);
-        if (out.getVersion().onOrAfter(Version.V_8_0_0)) {
+        if (out.getVersion().onOrAfter(Version.V_7_6_0)) {
             out.writeMap(meta, StreamOutput::writeString, (o, set) -> o.writeCollection(set, StreamOutput::writeString));
         }
     }