public MemberBuilder withProperty(String key, String value) {
    config.setProperty(key, value);
    return this;
  }
public MemberBuilder withProperty ( String key , String value ) { config . setProperty ( key , value ) ; return this ; }
Sets a member property.

@param key   the property key to set
@param value the property value to set
@return the member builder
@throws NullPointerException if the property is null