Changes to Estimate transfer

added the new required header request parameter Due-Account-Id to all path's operations

the request property destination/currency became required

the request property destination/rail became required

the request property source/currency became required

the request property source/rail became required

the destination/channelType request property type changed from string to object

the source/channelType request property type changed from string to object

added the new optional request property destination/channelType/NotNull

added the new optional request property destination/channelType/Val

added the new optional request property source/channelType/NotNull

added the new optional request property source/channelType/Val