code: boolean validateIssuer(String consumerConfigId, String issuers, String tokenIssuer) throws InvalidClaimException {
  		boolean isIssuer = false;
  		if (issuers == null || issuers.isEmpty()) {
  			String msg = Tr.formatMessage(tc, "JWT_TRUSTED_ISSUERS_NULL",
  					new Object[] { tokenIssuer, consumerConfigId });
  			throw new InvalidClaimException(msg);
  		}
  
  		StringTokenizer st = new StringTokenizer(issuers, ",");
  		while (st.hasMoreTokens()) {
  			String iss = st.nextToken().trim();
  			if (tc.isDebugEnabled()) {
  				Tr.debug(tc, "Trusted issuer: " + iss);
  			}
  			if (Constants.ALL_ISSUERS.equals(iss) || (tokenIssuer != null && tokenIssuer.equals(iss))) {
  				isIssuer = true;
  				break;
  			}
  		}
  
  		if (!isIssuer) {
  			String msg = Tr.formatMessage(tc, "JWT_ISSUER_NOT_TRUSTED",
  					new Object[] { tokenIssuer, consumerConfigId, issuers });
  			throw new InvalidClaimException(msg);
  		}
  		return isIssuer;
  	}
docs: Verifies that tokenIssuer is one of the values specified in the
  comma-separated issuers string.