code: public static Extension newExtension(ObjectIdentifier extensionId,
          boolean critical, byte[] rawExtensionValue) throws IOException {
          Extension ext = new Extension();
          ext.extensionId = extensionId;
          ext.critical = critical;
          ext.extensionValue = rawExtensionValue;
          return ext;
      }
docs: Constructs an Extension from individual components of ObjectIdentifier,
  criticality and the raw encoded extension value.
  
  @param extensionId the ObjectIdentifier of the extension
  @param critical the boolean indicating if the extension is critical
  @param rawExtensionValue the raw DER-encoded extension value (this
  is not the encoded OctetString).