Ensure PutMappingRequest.buildFromSimplifiedDef input are pairs

core/src/main/java/org/elasticsearch/action/admin/indices/mapping/put/PutMappingRequest.java

@@ -177,7 +177,17 @@ public PutMappingRequest source(Object... source) {
         return source(buildFromSimplifiedDef(type, source));
     }
 
+    /**
+     * @param type the mapping type
+     * @param source consisting of field/properties pairs (e.g. "field1",
+     *            "type=string,store=true"). If the number of arguments is not
+     *            divisible by two an {@link IllegalArgumentException} is thrown
+     * @return the mappings definition
+     */
     public static XContentBuilder buildFromSimplifiedDef(String type, Object... source) {
+        if (source.length % 2 != 0) {
+            throw new IllegalArgumentException("mapping source must be pairs of fieldnames and properties definition.");
+        }
         try {
             XContentBuilder builder = XContentFactory.jsonBuilder();
             builder.startObject();

core/src/test/java/org/elasticsearch/action/admin/indices/mapping/put/PutMappingRequestTests.java

@@ -57,4 +57,11 @@ public void testValidation() {
             "Validation Failed: 1: either concrete index or unresolved indices can be set," +
                 " concrete index: [[foo/bar]] and indices: [myindex];");
     }
+
+    public void testBuildFromSimplifiedDef() {
+        // test that method rejects input where input varargs fieldname/properites are not paired correctly
+        IllegalArgumentException e = expectThrows(IllegalArgumentException.class,
+                () -> PutMappingRequest.buildFromSimplifiedDef("type", "only_field"));
+        assertEquals("mapping source must be pairs of fieldnames and properties definition.", e.getMessage());
+    }
 }