@CanIgnoreReturnValue
    public Builder setCrtCoefficient(SecretBigInteger qInv) {
      this.qInv = qInv;
      return this;
    }
Sets the CRT coefficient qInv.

<p>See https://www.rfc-editor.org/rfc/rfc8017#section-3.2.

<p>This is required.
java_src/src/main/java/com/google/crypto/tink/signature/RsaSsaPkcs1PrivateKey.java