code: public ParallelTaskBuilder setSshPrivKeyRelativePath(
              String privKeyRelativePath) {
          this.sshMeta.setPrivKeyRelativePath(privKeyRelativePath);
          this.sshMeta.setSshLoginType(SshLoginType.KEY);
          return this;
      }
docs: Sets the ssh priv key relative path.
  Note that must be relative path for now.
  This default to no need of passphrase for the private key.
  Will also auto set the login type to key based.
  
  @param privKeyRelativePath
  the priv key relative path
  @return the parallel task builder