private static boolean validateLong(final JsonNode node) {
    if (!node.canConvertToLong()) {
      throw new IllegalArgumentException("Cannot convert value to long: " + node);
    }
    return true;
  }
Gets array node.

@param json the json
@param fieldKey the field key
@param strict true for strict mode
@return the array node
config/src/main/java/org/hyperledger/besu/config/JsonUtil.java