@CanIgnoreReturnValue
    public Builder setIssuer(String value) {
      if (!JsonUtil.isValidString(value)) {
        throw new IllegalArgumentException();
      }
      payload.add(JwtNames.CLAIM_ISSUER, new JsonPrimitive(value));
      return this;
    }
Sets the issuer claim that identifies the principal that issued the JWT.

<p>https://tools.ietf.org/html/rfc7519#section-4.1.1
java_src/src/main/java/com/google/crypto/tink/jwt/RawJwt.java