@JsonProperty("signingKeyString")
    public void setSigningKeyString(String signingKeyString) throws Exception {
        if (signingKey == null) {
            String[] schemes = {"http","https"};
            UrlValidator urlValidator = new UrlValidator(schemes, UrlValidator.ALLOW_LOCAL_URLS);
            // If it is a jwk(s) url we don't set the signingKey
            if (!urlValidator.isValid(signingKeyString)) {
                signingKey = PemUtils.decodePublicKey(signingKeyString);
            }
        }
        this.signingKeyString = signingKeyString;
    }
Signing Key
<p>
To validate JWT. Must be Base-64 encoded.

@param signingKeyString
           The signingKeyString
@throws Exception key parsing exceptions
plugins/jwt-policy/src/main/java/io/apiman/plugins/jwt/beans/JWTPolicyBean.java