"Vestas employees, suppliers and customers are encouraged to use our whistle-blower hotline, EthicsLine, to report observed or suspected misconduct. EthicsLine is hosted on a secure website where anyone can raise a concern...To date, there have been no cases on modern slavery"

pg. 3

"We have zero-tolerance for any form of retaliation against employees making a report in good faith, whether the report is ultimately substantiated or not. The same applies to individuals who cooperate as part of an Ethics Line investigation, such as witnesses."

The protection covers employees and suppliers (anyone who uses the whistleblower reporting system). The language is can be interpreted both ways (just employees or employees and suppliers) from the statement, but further documentation on the website clarifies that they mean both.