Remove references to 7.6 and 7.7 transport versions from ML model code

server/src/main/java/org/elasticsearch/TransportVersions.java

@@ -55,7 +55,6 @@ static TransportVersion def(int id) {
     public static final TransportVersion V_7_3_0 = def(7_03_00_99);
     public static final TransportVersion V_7_4_0 = def(7_04_00_99);
     public static final TransportVersion V_7_6_0 = def(7_06_00_99);
-    public static final TransportVersion V_7_7_0 = def(7_07_00_99);
     public static final TransportVersion V_7_8_0 = def(7_08_00_99);
     public static final TransportVersion V_7_8_1 = def(7_08_01_99);
     public static final TransportVersion V_7_9_0 = def(7_09_00_99);

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/ClassificationConfig.java

@@ -28,7 +28,6 @@ public class ClassificationConfig implements LenientlyParsedInferenceConfig, Str
     public static final ParseField NUM_TOP_FEATURE_IMPORTANCE_VALUES = new ParseField("num_top_feature_importance_values");
     public static final ParseField PREDICTION_FIELD_TYPE = new ParseField("prediction_field_type");
     private static final MlConfigVersion MIN_SUPPORTED_VERSION = MlConfigVersion.V_7_6_0;
-    private static final TransportVersion MIN_SUPPORTED_TRANSPORT_VERSION = TransportVersions.V_7_6_0;
 
     public static ClassificationConfig EMPTY_PARAMS = new ClassificationConfig(
         0,
@@ -227,7 +226,7 @@ public MlConfigVersion getMinimalSupportedMlConfigVersion() {
 
     @Override
     public TransportVersion getMinimalSupportedTransportVersion() {
-        return requestingImportance() ? TransportVersions.V_7_7_0 : MIN_SUPPORTED_TRANSPORT_VERSION;
+        return TransportVersions.ZERO;
     }
 
     public static Builder builder() {

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/RegressionConfig.java

@@ -23,7 +23,6 @@ public class RegressionConfig implements LenientlyParsedInferenceConfig, Strictl
 
     public static final ParseField NAME = new ParseField("regression");
     private static final MlConfigVersion MIN_SUPPORTED_VERSION = MlConfigVersion.V_7_6_0;
-    private static final TransportVersion MIN_SUPPORTED_TRANSPORT_VERSION = TransportVersions.V_7_6_0;
     public static final ParseField NUM_TOP_FEATURE_IMPORTANCE_VALUES = new ParseField("num_top_feature_importance_values");
 
     public static RegressionConfig EMPTY_PARAMS = new RegressionConfig(DEFAULT_RESULTS_FIELD, null);
@@ -160,7 +159,7 @@ public MlConfigVersion getMinimalSupportedMlConfigVersion() {
 
     @Override
     public TransportVersion getMinimalSupportedTransportVersion() {
-        return requestingImportance() ? TransportVersions.V_7_7_0 : MIN_SUPPORTED_TRANSPORT_VERSION;
+        return TransportVersions.ZERO;
     }
 
     public static Builder builder() {

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/TrainedModel.java

@@ -34,6 +34,6 @@ public interface TrainedModel extends NamedXContentObject, NamedWriteable, Accou
     long estimatedNumOperations();
 
     default TransportVersion getMinimalCompatibilityVersion() {
-        return TransportVersions.V_7_6_0;
+        return TransportVersions.ZERO;
     }
 }

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/ensemble/Ensemble.java

@@ -286,7 +286,7 @@ public TransportVersion getMinimalCompatibilityVersion() {
         return models.stream()
             .map(TrainedModel::getMinimalCompatibilityVersion)
             .max(TransportVersion::compareTo)
-            .orElse(TransportVersions.V_7_6_0);
+            .orElse(TransportVersions.ZERO);
     }
 
     public static class Builder {

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/inference/trainedmodel/tree/Tree.java

@@ -9,8 +9,6 @@
 import org.apache.lucene.util.Accountable;
 import org.apache.lucene.util.Accountables;
 import org.apache.lucene.util.RamUsageEstimator;
-import org.elasticsearch.TransportVersion;
-import org.elasticsearch.TransportVersions;
 import org.elasticsearch.common.Strings;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
@@ -287,14 +285,6 @@ public Collection<Accountable> getChildResources() {
         return Collections.unmodifiableCollection(accountables);
     }
 
-    @Override
-    public TransportVersion getMinimalCompatibilityVersion() {
-        if (nodes.stream().filter(TreeNode::isLeaf).anyMatch(t -> t.getLeafValue().length > 1)) {
-            return TransportVersions.V_7_7_0;
-        }
-        return TransportVersions.V_7_6_0;
-    }
-
     public static final class Builder {
         private List<String> featureNames;
         private ArrayList<TreeNode.Builder> nodes;

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/transform/transforms/TransformState.java

@@ -136,11 +136,7 @@ public TransformState(StreamInput in) throws IOException {
         reason = in.readOptionalString();
         progress = in.readOptionalWriteable(TransformProgress::new);
         node = in.readOptionalWriteable(NodeAttributes::new);
-        if (in.getTransportVersion().onOrAfter(TransportVersions.V_7_6_0)) {
-            shouldStopAtNextCheckpoint = in.readBoolean();
-        } else {
-            shouldStopAtNextCheckpoint = false;
-        }
+        shouldStopAtNextCheckpoint = in.readBoolean();
         if (in.getTransportVersion().onOrAfter(TransportVersions.V_8_8_0)) {
             authState = in.readOptionalWriteable(AuthorizationState::new);
         } else {
@@ -237,9 +233,7 @@ public void writeTo(StreamOutput out) throws IOException {
         out.writeOptionalString(reason);
         out.writeOptionalWriteable(progress);
         out.writeOptionalWriteable(node);
-        if (out.getTransportVersion().onOrAfter(TransportVersions.V_7_6_0)) {
-            out.writeBoolean(shouldStopAtNextCheckpoint);
-        }
+        out.writeBoolean(shouldStopAtNextCheckpoint);
         if (out.getTransportVersion().onOrAfter(TransportVersions.V_8_8_0)) {
             out.writeOptionalWriteable(authState);
         }