Is your feature request related to a problem? Please describe.
I am using ServiceAccountCredentials.Builder to parse my user provided credentials (via file / json). The setPrivateKey method accepts an instance of PrivateKey, where as the user provides a Pkcs8 string. The parsing method privateKeyFromPkcs8 is package private only. So, I have to make a copy of this method implementation in my package and use it. This is inconvenient and prone to error when if there are changes across versions.

Describe the solution you'd like
Can this parsing method privateKeyFromPkcs8 be made public ? Alternatively, can you provide a setPrivateKeyString method in the ServiceAccountCredentials.Builder class that will accept an Pkcs8 encoded string?