[ML] Add ML result classes to protocol library (#32587)

This commit adds the ML results classes to the X-Pack protocol
library used by the high level REST client.

(Other commits will add the config classes and stats classes.)

These classes:

- Are publically immutable
- Are privately mutable - this is perhaps not as nice as the
  config classes, but to do otherwise would require adding
  builders and the corresponding server-side classes that the
  old transport client used don't have builders
- Have little/no validation of field values beyond null checks
- Are convertible to and from X-Content, but NOT wire transportable
- Have lenient parsers to maximize compatibility across versions
- Have the same class names and getter names as the corresponding
  classes in X-Pack core to ease migration for transport client
  users
- Don't reproduce all the methods that do calculations or
  transformations that the the corresponding classes in X-Pack core
  have

x-pack/protocol/src/main/java/org/elasticsearch/protocol/xpack/ml/job/results/AnomalyCause.java

@@ -0,0 +1,292 @@
+/*
+ * Licensed to Elasticsearch under one or more contributor
+ * license agreements. See the NOTICE file distributed with
+ * this work for additional information regarding copyright
+ * ownership. Elasticsearch licenses this file to you under
+ * the Apache License, Version 2.0 (the "License"); you may
+ * not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ *    http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing,
+ * software distributed under the License is distributed on an
+ * "AS IS" BASIS, WITHOUT WARRANTIES OR CONDITIONS OF ANY
+ * KIND, either express or implied.  See the License for the
+ * specific language governing permissions and limitations
+ * under the License.
+ */
+package org.elasticsearch.protocol.xpack.ml.job.results;
+
+import org.elasticsearch.common.ParseField;
+import org.elasticsearch.common.xcontent.ObjectParser;
+import org.elasticsearch.common.xcontent.ToXContentObject;
+import org.elasticsearch.common.xcontent.XContentBuilder;
+
+import java.io.IOException;
+import java.util.Collections;
+import java.util.List;
+import java.util.Objects;
+
+/**
+ * Anomaly Cause POJO.
+ * Used as a nested level inside population anomaly records.
+ */
+public class AnomalyCause implements ToXContentObject {
+
+    public static final ParseField ANOMALY_CAUSE = new ParseField("anomaly_cause");
+
+    /**
+     * Result fields
+     */
+    public static final ParseField PROBABILITY = new ParseField("probability");
+    public static final ParseField OVER_FIELD_NAME = new ParseField("over_field_name");
+    public static final ParseField OVER_FIELD_VALUE = new ParseField("over_field_value");
+    public static final ParseField BY_FIELD_NAME = new ParseField("by_field_name");
+    public static final ParseField BY_FIELD_VALUE = new ParseField("by_field_value");
+    public static final ParseField CORRELATED_BY_FIELD_VALUE = new ParseField("correlated_by_field_value");
+    public static final ParseField PARTITION_FIELD_NAME = new ParseField("partition_field_name");
+    public static final ParseField PARTITION_FIELD_VALUE = new ParseField("partition_field_value");
+    public static final ParseField FUNCTION = new ParseField("function");
+    public static final ParseField FUNCTION_DESCRIPTION = new ParseField("function_description");
+    public static final ParseField TYPICAL = new ParseField("typical");
+    public static final ParseField ACTUAL = new ParseField("actual");
+    public static final ParseField INFLUENCERS = new ParseField("influencers");
+
+    /**
+     * Metric Results
+     */
+    public static final ParseField FIELD_NAME = new ParseField("field_name");
+
+    public static final ObjectParser<AnomalyCause, Void> PARSER =
+        new ObjectParser<>(ANOMALY_CAUSE.getPreferredName(), true, AnomalyCause::new);
+
+    static {
+        PARSER.declareDouble(AnomalyCause::setProbability, PROBABILITY);
+        PARSER.declareString(AnomalyCause::setByFieldName, BY_FIELD_NAME);
+        PARSER.declareString(AnomalyCause::setByFieldValue, BY_FIELD_VALUE);
+        PARSER.declareString(AnomalyCause::setCorrelatedByFieldValue, CORRELATED_BY_FIELD_VALUE);
+        PARSER.declareString(AnomalyCause::setPartitionFieldName, PARTITION_FIELD_NAME);
+        PARSER.declareString(AnomalyCause::setPartitionFieldValue, PARTITION_FIELD_VALUE);
+        PARSER.declareString(AnomalyCause::setFunction, FUNCTION);
+        PARSER.declareString(AnomalyCause::setFunctionDescription, FUNCTION_DESCRIPTION);
+        PARSER.declareDoubleArray(AnomalyCause::setTypical, TYPICAL);
+        PARSER.declareDoubleArray(AnomalyCause::setActual, ACTUAL);
+        PARSER.declareString(AnomalyCause::setFieldName, FIELD_NAME);
+        PARSER.declareString(AnomalyCause::setOverFieldName, OVER_FIELD_NAME);
+        PARSER.declareString(AnomalyCause::setOverFieldValue, OVER_FIELD_VALUE);
+        PARSER.declareObjectArray(AnomalyCause::setInfluencers, Influence.PARSER, INFLUENCERS);
+    }
+
+    private double probability;
+    private String byFieldName;
+    private String byFieldValue;
+    private String correlatedByFieldValue;
+    private String partitionFieldName;
+    private String partitionFieldValue;
+    private String function;
+    private String functionDescription;
+    private List<Double> typical;
+    private List<Double> actual;
+    private String fieldName;
+    private String overFieldName;
+    private String overFieldValue;
+
+    private List<Influence> influencers;
+
+    AnomalyCause() {
+    }
+
+    @Override
+    public XContentBuilder toXContent(XContentBuilder builder, Params params) throws IOException {
+        builder.startObject();
+        builder.field(PROBABILITY.getPreferredName(), probability);
+        if (byFieldName != null) {
+            builder.field(BY_FIELD_NAME.getPreferredName(), byFieldName);
+        }
+        if (byFieldValue != null) {
+            builder.field(BY_FIELD_VALUE.getPreferredName(), byFieldValue);
+        }
+        if (correlatedByFieldValue != null) {
+            builder.field(CORRELATED_BY_FIELD_VALUE.getPreferredName(), correlatedByFieldValue);
+        }
+        if (partitionFieldName != null) {
+            builder.field(PARTITION_FIELD_NAME.getPreferredName(), partitionFieldName);
+        }
+        if (partitionFieldValue != null) {
+            builder.field(PARTITION_FIELD_VALUE.getPreferredName(), partitionFieldValue);
+        }
+        if (function != null) {
+            builder.field(FUNCTION.getPreferredName(), function);
+        }
+        if (functionDescription != null) {
+            builder.field(FUNCTION_DESCRIPTION.getPreferredName(), functionDescription);
+        }
+        if (typical != null) {
+            builder.field(TYPICAL.getPreferredName(), typical);
+        }
+        if (actual != null) {
+            builder.field(ACTUAL.getPreferredName(), actual);
+        }
+        if (fieldName != null) {
+            builder.field(FIELD_NAME.getPreferredName(), fieldName);
+        }
+        if (overFieldName != null) {
+            builder.field(OVER_FIELD_NAME.getPreferredName(), overFieldName);
+        }
+        if (overFieldValue != null) {
+            builder.field(OVER_FIELD_VALUE.getPreferredName(), overFieldValue);
+        }
+        if (influencers != null) {
+            builder.field(INFLUENCERS.getPreferredName(), influencers);
+        }
+        builder.endObject();
+        return builder;
+    }
+
+    public double getProbability() {
+        return probability;
+    }
+
+    void setProbability(double value) {
+        probability = value;
+    }
+
+    public String getByFieldName() {
+        return byFieldName;
+    }
+
+    void setByFieldName(String value) {
+        byFieldName = value;
+    }
+
+    public String getByFieldValue() {
+        return byFieldValue;
+    }
+
+    void setByFieldValue(String value) {
+        byFieldValue = value;
+    }
+
+    public String getCorrelatedByFieldValue() {
+        return correlatedByFieldValue;
+    }
+
+    void setCorrelatedByFieldValue(String value) {
+        correlatedByFieldValue = value;
+    }
+
+    public String getPartitionFieldName() {
+        return partitionFieldName;
+    }
+
+    void setPartitionFieldName(String field) {
+        partitionFieldName = field;
+    }
+
+    public String getPartitionFieldValue() {
+        return partitionFieldValue;
+    }
+
+    void setPartitionFieldValue(String value) {
+        partitionFieldValue = value;
+    }
+
+    public String getFunction() {
+        return function;
+    }
+
+    void setFunction(String name) {
+        function = name;
+    }
+
+    public String getFunctionDescription() {
+        return functionDescription;
+    }
+
+    void setFunctionDescription(String functionDescription) {
+        this.functionDescription = functionDescription;
+    }
+
+    public List<Double> getTypical() {
+        return typical;
+    }
+
+    void setTypical(List<Double> typical) {
+        this.typical = Collections.unmodifiableList(typical);
+    }
+
+    public List<Double> getActual() {
+        return actual;
+    }
+
+    void setActual(List<Double> actual) {
+        this.actual = Collections.unmodifiableList(actual);
+    }
+
+    public String getFieldName() {
+        return fieldName;
+    }
+
+    void setFieldName(String field) {
+        fieldName = field;
+    }
+
+    public String getOverFieldName() {
+        return overFieldName;
+    }
+
+    void setOverFieldName(String name) {
+        overFieldName = name;
+    }
+
+    public String getOverFieldValue() {
+        return overFieldValue;
+    }
+
+    void setOverFieldValue(String value) {
+        overFieldValue = value;
+    }
+
+    public List<Influence> getInfluencers() {
+        return influencers;
+    }
+
+    void setInfluencers(List<Influence> influencers) {
+        this.influencers = Collections.unmodifiableList(influencers);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(probability, actual, typical, byFieldName, byFieldValue, correlatedByFieldValue, fieldName, function,
+            functionDescription, overFieldName, overFieldValue, partitionFieldName, partitionFieldValue, influencers);
+    }
+
+    @Override
+    public boolean equals(Object other) {
+        if (this == other) {
+            return true;
+        }
+
+        if (other == null || getClass() != other.getClass()) {
+            return false;
+        }
+
+        AnomalyCause that = (AnomalyCause)other;
+
+        return this.probability == that.probability &&
+            Objects.equals(this.typical, that.typical) &&
+            Objects.equals(this.actual, that.actual) &&
+            Objects.equals(this.function, that.function) &&
+            Objects.equals(this.functionDescription, that.functionDescription) &&
+            Objects.equals(this.fieldName, that.fieldName) &&
+            Objects.equals(this.byFieldName, that.byFieldName) &&
+            Objects.equals(this.byFieldValue, that.byFieldValue) &&
+            Objects.equals(this.correlatedByFieldValue, that.correlatedByFieldValue) &&
+            Objects.equals(this.partitionFieldName, that.partitionFieldName) &&
+            Objects.equals(this.partitionFieldValue, that.partitionFieldValue) &&
+            Objects.equals(this.overFieldName, that.overFieldName) &&
+            Objects.equals(this.overFieldValue, that.overFieldValue) &&
+            Objects.equals(this.influencers, that.influencers);
+    }
+}