To set Header using groovy script in SAP CPI/ SAP HCI

You can add this below script and achieve to add the header to the content

import com.sap.gateway.ip.core.customdev.util.Message;

import java.util.HashMap;

def Message processData(Message message) {

  message.setHeader("Content-Type", "text/xml" + "; charset=utf-8" );

  return message;

}