code: private static boolean validateBeanPath(final CharSequence path) {
          final int pathLen = path.length();
          boolean inKey = false;
          for (int charPos = 0; charPos < pathLen; charPos++) {
              final char c = path.charAt(charPos);
              if (!inKey && c == PropertyAccessor.PROPERTY_KEY_PREFIX_CHAR) {
                  inKey = true;
              }
              else if (inKey && c == PropertyAccessor.PROPERTY_KEY_SUFFIX_CHAR) {
                  inKey = false;
              }
              else if (!inKey && !Character.isJavaIdentifierPart(c) && c != '.') {
                  return false;
              }
          }
          return true;
      }
docs: /*
  This method determines whether a fragment of a bean path is a valid bean property identifier
  or bean property expression.