getProperty method in the aggregations framework now throws a specific exception

src/main/java/org/elasticsearch/search/aggregations/InternalMultiBucketAggregation.java

@@ -19,7 +19,6 @@
 
 package org.elasticsearch.search.aggregations;
 
-import org.elasticsearch.ElasticsearchIllegalArgumentException;
 import org.elasticsearch.search.aggregations.bucket.MultiBucketsAggregation;
 import org.elasticsearch.search.aggregations.reducers.Reducer;
 
@@ -58,18 +57,19 @@ public abstract class InternalMultiBucketAggregation extends InternalAggregation
             String aggName = path.get(0);
             if (aggName.equals("_count")) {
                 if (path.size() > 1) {
-                    throw new ElasticsearchIllegalArgumentException("_count must be the last element in the path");
+                    throw new InvalidAggregationPathException("_count must be the last element in the path");
                 }
                 return getDocCount();
             } else if (aggName.equals("_key")) {
                 if (path.size() > 1) {
-                    throw new ElasticsearchIllegalArgumentException("_key must be the last element in the path");
+                    throw new InvalidAggregationPathException("_key must be the last element in the path");
                 }
                 return getKey();
             }
             InternalAggregation aggregation = aggregations.get(aggName);
             if (aggregation == null) {
-                throw new ElasticsearchIllegalArgumentException("Cannot find an aggregation named [" + aggName + "] in [" + containingAggName + "]");
+                throw new InvalidAggregationPathException("Cannot find an aggregation named [" + aggName + "] in [" + containingAggName
+                        + "]");
             }
             return aggregation.getProperty(path.subList(1, path.size()));
         }

src/main/java/org/elasticsearch/search/aggregations/InvalidAggregationPathException.java

@@ -0,0 +1,33 @@
+/*
+ * 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.search.aggregations;
+
+import org.elasticsearch.ElasticsearchException;
+
+public class InvalidAggregationPathException extends ElasticsearchException {
+
+    public InvalidAggregationPathException(String msg) {
+        super(msg);
+    }
+
+    public InvalidAggregationPathException(String msg, Throwable cause) {
+        super(msg, cause);
+    }
+}