public ApiClient addDefaultHeader(String key, String value) {
    defaultHeaderMap.put(key, value);
    return this;
  }
public ApiClient addDefaultHeader(String key, String value) {
    defaultHeaderMap.put(key, value);
    return this;
  }
public ApiClient addDefaultHeader ( String key , String value ) { defaultHeaderMap . put ( key , value ) ; return this ; }
Add a default header.

@param key The header's key
@param value The header's value
Add a default header .