suspend fun convertForSend(
context: PipelineContext<Any, ApplicationCall>,
Convert a value to the specified contentType to a value suitable for sending (serialize).
Note that as far as ContentConverter could be registered multiple times with different content types
hence contentType could be different depends on what the client accepts (inferred from Accept header).
This function could ignore value if it is not suitable for conversion and return
null so in this case
other registered converters could be tried or this function could be invoked with other content types
it the converted has been registered multiple times with different content types
context - pipeline context
contentType - to which this data converted has been registered and that matches client’s accept header
value - to be converted