SOLR-13780: fix ClassCastException in NestableJsonFacet

* handle both int and long values for count. In case of single-shard or
  standalone, count is int whereas in multishard count would be long

solr/CHANGES.txt

@@ -222,6 +222,8 @@ Bug Fixes
 
 * SOLR-13238: BlobHandler generates non-padded md5 (Jeff Walraven via janhoy)
 
+* SOLR-13780: Fix ClassCastException in NestableJsonFacet (Tiago Martinho de Barros, Munendra S N)
+
 Other Changes
 ----------------------
 

solr/solrj/src/java/org/apache/solr/client/solrj/response/json/NestableJsonFacet.java

@@ -49,7 +49,7 @@ public class NestableJsonFacet {
       if (getKeysToSkip().contains(key)) {
         continue;
       } else if ("count".equals(key)) {
-        domainCount = (int) entry.getValue();
+        domainCount = ((Number) entry.getValue()).longValue();
       } else if(entry.getValue() instanceof Number) { // Stat/agg facet value
         statFacetsByName.put(key, (Number)entry.getValue());
       } else if(entry.getValue() instanceof NamedList) { // Either heatmap/query/range/terms facet

solr/solrj/src/test/org/apache/solr/client/solrj/response/NestableJsonFacetTest.java

@@ -0,0 +1,85 @@
+/*
+ * Licensed to the Apache Software Foundation (ASF) under one or more
+ * contributor license agreements.  See the NOTICE file distributed with
+ * this work for additional information regarding copyright ownership.
+ * The ASF 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.apache.solr.client.solrj.response;
+
+
+import java.util.Collections;
+
+import org.apache.solr.SolrTestCaseJ4;
+import org.apache.solr.client.solrj.response.json.NestableJsonFacet;
+import org.apache.solr.common.util.NamedList;
+import org.junit.Test;
+
+public class NestableJsonFacetTest extends SolrTestCaseJ4 {
+
+  @Test
+  public void testParsing() {
+    NamedList<Object> list = new NamedList<>();
+    list.add("count", 12);
+    NamedList<Object> buckets = new NamedList<Object>() {{
+      add("val", "Nike");
+    }};
+    NamedList<Object> vals = new NamedList<Object>() {{
+      add("numBuckets", 10);
+      add("allBuckets", new NamedList<Object>(){{
+        add("count", 12);
+      }});
+      add("before", new NamedList<Object>(){{
+        add("count", 1);
+      }});
+      add("after", new NamedList<Object>(){{
+        add("count", 2);
+      }});
+      add("between", new NamedList<Object>(){{
+        add("count", 9);
+      }});
+    }};
+    vals.add("buckets", Collections.singletonList(buckets));
+    list.add("test", vals);
+    NestableJsonFacet facet = new NestableJsonFacet(list);
+
+    assertEquals(12L, facet.getCount());
+    assertEquals(9L, facet.getBucketBasedFacets("test").getBetween());
+    list.clear();
+
+    list.add("count", 12L);
+    buckets = new NamedList<Object>() {{
+      add("val", "Nike");
+    }};
+    vals = new NamedList<Object>() {{
+      add("numBuckets", 10L);
+      add("allBuckets", new NamedList<Object>(){{
+        add("count", 12L);
+      }});
+      add("before", new NamedList<Object>(){{
+        add("count", 1L);
+      }});
+      add("after", new NamedList<Object>(){{
+        add("count", 2L);
+      }});
+      add("between", new NamedList<Object>(){{
+        add("count", 9L);
+      }});
+    }};
+    vals.add("buckets", Collections.singletonList(buckets));
+    list.add("test", vals);
+    facet = new NestableJsonFacet(list);
+    assertEquals(12L, facet.getCount());
+    assertEquals(2L, facet.getBucketBasedFacets("test").getAfter());
+  }
+}