docs: private org.mariadb.jdbc.internal.com.send.authentication.ed25519.math.GroupElement madd(
        org.mariadb.jdbc.internal.com.send.authentication.ed25519.math.GroupElement q) {
      if (this.repr != Representation.P3) {
        throw new UnsupportedOperationException();
      }
      if (q.repr != Representation.PRECOMP) {
        throw new IllegalArgumentException();
      }
  
      FieldElement YpX, YmX, A, B, C, D;
      YpX = this.Y.add(this.X);
      YmX = this.Y.subtract(this.X);
      A = YpX.multiply(q.X); // q->y+x
      B = YmX.multiply(q.Y); // q->y-x
      C = q.Z.multiply(this.T); // q->2dxy
      D = this.Z.add(this.Z);
      return p1p1(this.curve, A.subtract(B), A.add(B), D.add(C), D.subtract(C));
    }