Check two Headers field name and field value equality.

Weather the field is singleton field or not.

Merge two Headers object. The first Headers always takes precedence. When fields conflict, the first Headers takes precedence if it is a singleton field. If it is a list-based field and not empty, it is appended to the first Headers field. Invalid field names and field values are ignored. No destructive operation is performed on the arguments and returns a new Headers object.

Parse the header field value. Split field values by <quoted-string> or <token>.

Header merge options.

Wellknown HTTP field name.

Custom merge definition.