Fix compilation after upstream Elasticsearch changes (elastic/elasticsearch#621)

The Elasticsearch change that caused the breakage was
73625f6291

Original commit: elastic/x-pack-elasticsearch@01b82a79d4

elasticsearch/src/main/java/org/elasticsearch/xpack/prelert/PrelertPlugin.java

@@ -137,10 +137,6 @@ public class PrelertPlugin extends Plugin implements ActionPlugin {
 
     private final ParseFieldMatcherSupplier parseFieldMatcherSupplier;
 
-    static {
-        MetaData.registerPrototype(PrelertMetadata.TYPE, PrelertMetadata.PROTO);
-    }
-
     public PrelertPlugin(Settings settings) {
         this.settings = settings;
         this.env = new Environment(settings);

elasticsearch/src/main/java/org/elasticsearch/xpack/prelert/job/Job.java

@@ -23,7 +23,6 @@ import org.elasticsearch.xpack.prelert.job.messages.Messages;
 import org.elasticsearch.xpack.prelert.job.transform.TransformConfig;
 import org.elasticsearch.xpack.prelert.job.transform.TransformConfigs;
 import org.elasticsearch.xpack.prelert.job.transform.verification.TransformConfigsVerifier;
-import org.elasticsearch.xpack.prelert.utils.ExceptionsHelper;
 import org.elasticsearch.xpack.prelert.utils.PrelertStrings;
 import org.elasticsearch.xpack.prelert.utils.time.TimeUtils;
 
@@ -196,11 +195,6 @@ public class Job extends AbstractDiffable<Job> implements Writeable, ToXContent
         indexName = in.readString();
     }
 
-    @Override
-    public Job readFrom(StreamInput in) throws IOException {
-        return new Job(in);
-    }
-
     /**
      * Return the Job Id.
      *

elasticsearch/src/main/java/org/elasticsearch/xpack/prelert/job/metadata/Allocation.java

@@ -87,11 +87,6 @@ public class Allocation extends AbstractDiffable<Allocation> implements ToXConte
         return statusReason;
     }
 
-    @Override
-    public Allocation readFrom(StreamInput in) throws IOException {
-        return new Allocation(in);
-    }
-
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         out.writeOptionalString(nodeId);

elasticsearch/src/main/java/org/elasticsearch/xpack/prelert/job/metadata/PrelertMetadata.java

@@ -12,7 +12,6 @@ import org.elasticsearch.cluster.DiffableUtils;
 import org.elasticsearch.cluster.metadata.MetaData;
 import org.elasticsearch.common.Nullable;
 import org.elasticsearch.common.ParseField;
-import org.elasticsearch.common.ParseFieldMatcher;
 import org.elasticsearch.common.ParseFieldMatcherSupplier;
 import org.elasticsearch.common.io.stream.StreamInput;
 import org.elasticsearch.common.io.stream.StreamOutput;
@@ -20,7 +19,6 @@ import org.elasticsearch.common.io.stream.Writeable;
 import org.elasticsearch.common.xcontent.ObjectParser;
 import org.elasticsearch.common.xcontent.ToXContent;
 import org.elasticsearch.common.xcontent.XContentBuilder;
-import org.elasticsearch.common.xcontent.XContentParser;
 import org.elasticsearch.search.SearchRequestParsers;
 import org.elasticsearch.xpack.prelert.job.Job;
 import org.elasticsearch.xpack.prelert.job.JobStatus;
@@ -89,15 +87,10 @@ public class PrelertMetadata implements MetaData.Custom {
     }
 
     @Override
-    public String type() {
+    public String getWriteableName() {
         return TYPE;
     }
 
-    @Override
-    public MetaData.Custom fromXContent(XContentParser parser) throws IOException {
-        return PRELERT_METADATA_PARSER.parse(parser, () -> ParseFieldMatcher.STRICT).build();
-    }
-
     @Override
     public EnumSet<MetaData.XContentContext> context() {
         // NORELEASE: Also include SNAPSHOT, but then we need to split the allocations from here and add them
@@ -110,29 +103,25 @@ public class PrelertMetadata implements MetaData.Custom {
         return new PrelertMetadataDiff((PrelertMetadata) previousState, this);
     }
 
-    @Override
+    public PrelertMetadata(StreamInput in) throws IOException {
-    public Diff<MetaData.Custom> readDiffFrom(StreamInput in) throws IOException {
-        return new PrelertMetadataDiff(in);
-    }
-
-    @Override
-    public MetaData.Custom readFrom(StreamInput in) throws IOException {
         int size = in.readVInt();
         TreeMap<String, Job> jobs = new TreeMap<>();
         for (int i = 0; i < size; i++) {
             jobs.put(in.readString(), new Job(in));
         }
+        this.jobs = jobs;
         size = in.readVInt();
         TreeMap<String, Allocation> allocations = new TreeMap<>();
         for (int i = 0; i < size; i++) {
-            allocations.put(in.readString(), Allocation.PROTO.readFrom(in));
+            allocations.put(in.readString(), new Allocation(in));
         }
+        this.allocations = allocations;
         size = in.readVInt();
         TreeMap<String, Scheduler> schedulers = new TreeMap<>();
         for (int i = 0; i < size; i++) {
             schedulers.put(in.readString(), new Scheduler(in));
         }
-        return new PrelertMetadata(jobs, allocations, schedulers);
+        this.schedulers = schedulers;
     }
 
     @Override
@@ -179,12 +168,6 @@ public class PrelertMetadata implements MetaData.Custom {
             this.schedulers = DiffableUtils.diff(before.schedulers, after.schedulers, DiffableUtils.getStringKeySerializer());
         }
 
-        PrelertMetadataDiff(StreamInput in) throws IOException {
-            jobs = DiffableUtils.readJdkMapDiff(in, DiffableUtils.getStringKeySerializer(), Job.PROTO);
-            allocations = DiffableUtils.readJdkMapDiff(in, DiffableUtils.getStringKeySerializer(), Allocation.PROTO);
-            schedulers = DiffableUtils.readJdkMapDiff(in, DiffableUtils.getStringKeySerializer(), Scheduler.PROTO);
-        }
-
         @Override
         public MetaData.Custom apply(MetaData.Custom part) {
             TreeMap<String, Job> newJobs = new TreeMap<>(jobs.apply(((PrelertMetadata) part).jobs));

elasticsearch/src/main/java/org/elasticsearch/xpack/prelert/scheduler/Scheduler.java

@@ -66,11 +66,6 @@ public class Scheduler extends AbstractDiffable<Scheduler> implements ToXContent
         return status;
     }
 
-    @Override
-    public Scheduler readFrom(StreamInput in) throws IOException {
-        return new Scheduler(in);
-    }
-
     @Override
     public void writeTo(StreamOutput out) throws IOException {
         config.writeTo(out);

elasticsearch/src/test/java/org/elasticsearch/xpack/prelert/job/metadata/PrelertMetadataTests.java

@@ -68,7 +68,7 @@ public class PrelertMetadataTests extends AbstractSerializingTestCase<PrelertMet
 
     @Override
     protected Writeable.Reader<PrelertMetadata> instanceReader() {
-        return in -> (PrelertMetadata) PrelertMetadata.PROTO.readFrom(in);
+        return in -> new PrelertMetadata(in);
     }
 
     @Override