[ML] adjusting for backport (#36117)

Author: benwtrent

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/datafeed/DatafeedConfig.java

@@ -13,7 +13,6 @@
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
 import org.elasticsearch.common.unit.TimeValue;
-import org.elasticsearch.common.util.CachedSupplier;
 import org.elasticsearch.common.xcontent.ObjectParser;
 import org.elasticsearch.common.xcontent.ToXContentObject;
 import org.elasticsearch.common.xcontent.XContentBuilder;
@@ -30,6 +29,7 @@
 import org.elasticsearch.xpack.core.ml.datafeed.extractor.ExtractorUtils;
 import org.elasticsearch.xpack.core.ml.job.config.Job;
 import org.elasticsearch.xpack.core.ml.job.messages.Messages;
+import org.elasticsearch.xpack.core.ml.utils.CachedSupplier;
 import org.elasticsearch.xpack.core.ml.utils.ExceptionsHelper;
 import org.elasticsearch.xpack.core.ml.utils.MlStrings;
 import org.elasticsearch.xpack.core.ml.utils.ToXContentParams;
@@ -256,7 +256,7 @@ public DatafeedConfig(StreamInput in) throws IOException {
         } else {
             this.types = null;
         }
-        if (in.getVersion().before(Version.CURRENT)) {
+        if (in.getVersion().before(Version.V_6_6_0)) {
             this.query = QUERY_TRANSFORMER.toMap(in.readNamedWriteable(QueryBuilder.class));
             this.aggregations = AGG_TRANSFORMER.toMap(in.readOptionalWriteable(AggregatorFactories.Builder::new));
         } else {
@@ -384,7 +384,7 @@ public void writeTo(StreamOutput out) throws IOException {
         } else {
             out.writeBoolean(false);
         }
-        if (out.getVersion().before(Version.CURRENT)) {
+        if (out.getVersion().before(Version.V_6_6_0)) {
             out.writeNamedWriteable(getParsedQuery());
             out.writeOptionalWriteable(getParsedAggregations());
         } else {

x-pack/plugin/core/src/main/java/org/elasticsearch/xpack/core/ml/utils/CachedSupplier.java

@@ -0,0 +1,29 @@
+package org.elasticsearch.xpack.core.ml.utils;
+
+import java.util.function.Supplier;
+
+/**
+ * A {@link Supplier} that caches its return value. This may be useful to make
+ * a {@link Supplier} idempotent or for performance reasons if always returning
+ * the same instance is acceptable.
+ */
+public final class CachedSupplier<T> implements Supplier<T> {
+
+    private Supplier<T> supplier;
+    private T result;
+    private boolean resultSet;
+
+    public CachedSupplier(Supplier<T> supplier) {
+        this.supplier = supplier;
+    }
+
+    @Override
+    public synchronized T get() {
+        if (resultSet == false) {
+            result = supplier.get();
+            resultSet = true;
+        }
+        return result;
+    }
+
+}