toResponseBody
Returns a new response body that transmits this string. If contentType is non-null and has a charset other than utf-8 the behaviour differs by platform.
On the JVM the encoding will be used instead of utf-8.
On non JVM platforms, this method will fail for encodings other than utf-8.
Returns a new response body that transmits this byte array.
Returns a new response body that transmits this byte string.