This member is added by an implicit conversion from WithFixedCharset to
any2stringadd[WithFixedCharset] performed by method any2stringadd in scala.Predef.
This member is added by an implicit conversion from WithFixedCharset to
StringFormat[WithFixedCharset] performed by method StringFormat in scala.Predef.
Represents a content-type which we know to contain text, where the charset always has the same predefined value.