Prior to version 7.0, indexes could contain a custom type. In version 6.x, only a single index type is allowed for an index. In version 6.7, a dummy index type, _doc, is used if no index type is specified. However, APIs in 7.0 are typeless but the type name _doc is still valid. A new include_type_name URL parameter to support the old custom type index is introduced in version 6.7.
The default value is true since the type name is still required in version 6.7. In version 7.0, the default value is false. To work with the old custom index type, you can attach the include_type_name=false URL parameter.
You can skip the custom type in the URL since the typeless GET API is used. An example of retrieving index mappings without specifying the index type in the URL is shown in the following screenshot:
In the response body, no index...
