spring-data-jest/src/main/java/com/github/vanroy/springdata/jest/MappingBuilder.java
private static void addMultiFieldMapping(
			XContentBuilder builder,
			java.lang.reflect.Field field,
			MultiField annotation,
			boolean nestedOrObjectField) throws IOException {

		// main field
		builder.startObject(field.getName());
		addFieldMappingParameters(builder, annotation.mainField(), nestedOrObjectField);

		// inner fields
		builder.startObject("fields");
		for (InnerField innerField : annotation.otherFields()) {
			builder.startObject(innerField.suffix());
			addFieldMappingParameters(builder, innerField, false);
			builder.endObject();
		}
		builder.endObject();

		builder.endObject();
	}
private static void addMultiFieldMapping(
			XContentBuilder builder,
			java.lang.reflect.Field field,
			MultiField annotation,
			boolean nestedOrObjectField) throws IOException {

		// main field
		builder.startObject(field.getName());
		addFieldMappingParameters(builder, annotation.mainField(), nestedOrObjectField);

		// inner fields
		builder.startObject("fields");
		for (InnerField innerField : annotation.otherFields()) {
			builder.startObject(innerField.suffix());
			addFieldMappingParameters(builder, innerField, false);
			builder.endObject();
		}
		builder.endObject();

		builder.endObject();
	}
Add mapping for @MultiField annotation

@throws IOException