Fix updating include_in_parent/include_in_root of nested field.

server/src/main/java/org/elasticsearch/index/mapper/ObjectMapper.java

@@ -465,9 +465,7 @@ protected void doMerge(final ObjectMapper mergeWith) {
             this.dynamic = mergeWith.dynamic;
         }
 
-        if (isEnabled() != mergeWith.isEnabled()) {
-            throw new MapperException("The [enabled] parameter can't be updated for the object mapping [" + name() + "].");
-        }
+        checkObjectMapperParameters(mergeWith);
 
         for (Mapper mergeWithMapper : mergeWith) {
             Mapper mergeIntoMapper = mappers.get(mergeWithMapper.simpleName());
@@ -484,6 +482,22 @@ protected void doMerge(final ObjectMapper mergeWith) {
         }
     }
 
+    private void checkObjectMapperParameters(final ObjectMapper mergeWith) {
+        if (isEnabled() != mergeWith.isEnabled()) {
+            throw new MapperException("The [enabled] parameter can't be updated for the object mapping [" + name() + "].");
+        }
+
+        if (nested().isIncludeInParent() != mergeWith.nested().isIncludeInParent()) {
+            throw new MapperException("The [include_in_parent] parameter can't be updated for the nested object mapping [" +
+                name() + "].");
+        }
+
+        if (nested().isIncludeInRoot() != mergeWith.nested().isIncludeInRoot()) {
+            throw new MapperException("The [include_in_root] parameter can't be updated for the nested object mapping [" +
+                name() + "].");
+        }
+    }
+
     @Override
     public ObjectMapper updateFieldType(Map<String, MappedFieldType> fullNameToFieldType) {
         List<Mapper> updatedMappers = null;

server/src/test/java/org/elasticsearch/index/mapper/NestedObjectMapperTests.java

@@ -742,4 +742,40 @@ public void testReorderParent() throws IOException {
         assertThat(doc.docs().get(1).get("nested1.field2"), equalTo("4"));
         assertThat(doc.docs().get(2).get("field"), equalTo("value"));
     }
+
+    public void testMergeNestedMappings() throws  IOException {
+        MapperService mapperService = createIndex("index1", Settings.EMPTY, jsonBuilder().startObject()
+            .startObject("properties")
+                .startObject("nested1")
+                    .field("type", "nested")
+                .endObject()
+            .endObject().endObject()).mapperService();
+        ObjectMapper objectMapper1 = mapperService.getObjectMapper("nested1");
+
+        mapperService = createIndex("index2", Settings.EMPTY, jsonBuilder().startObject()
+            .startObject("properties")
+                .startObject("nested1")
+                    .field("type", "nested")
+                    .field("include_in_parent", true)
+                .endObject()
+            .endObject().endObject()).mapperService();
+        ObjectMapper objectMapper2 = mapperService.getObjectMapper("nested1");
+
+        // cannot update `include_in_parent` dynamically
+        MapperException e1 = expectThrows(MapperException.class, () -> objectMapper1.merge(objectMapper2));
+        assertEquals("The [include_in_parent] parameter can't be updated for the nested object mapping [nested1].", e1.getMessage());
+
+        mapperService = createIndex("index3", Settings.EMPTY, jsonBuilder().startObject()
+            .startObject("properties")
+                .startObject("nested1")
+                    .field("type", "nested")
+                    .field("include_in_root", true)
+                .endObject()
+            .endObject().endObject()).mapperService();
+        ObjectMapper objectMapper3 = mapperService.getObjectMapper("nested1");
+
+        // cannot update `include_in_root` dynamically
+        MapperException e2 = expectThrows(MapperException.class, () -> objectMapper1.merge(objectMapper3));
+        assertEquals("The [include_in_root] parameter can't be updated for the nested object mapping [nested1].", e2.getMessage());
+    }
 }