Germany here. The whistleblowing process to report wrongdoing generally involves a lawyers who receives the claim(s), filters the matter and forwards the case. The anonimity of the whistleblowers is always guaranteed as the lawyer’s documents cannot be obtained by the company.
What happened in this case, is that the local prosecutor leveraged Section 97(1)(3) of the Code of Criminal Procedure to seize such documents; consequently, the lawyer refused the seizure according to the same provision.
Yet, there is no client-lawyer relationship, as the lawyer is directly serving the company and not the employee.