code: static boolean isPossibleQualifiedName(@Nonnull String value, @Nonnull String extraAllowedCharacters) {
          // package-info violates the spec for Java Identifiers.
          // Nevertheless, expressions that end with this string are still legal.
          // See 7.4.1.1 of the Java language spec for discussion.
          if (value.endsWith(PACKAGE_INFO)) {
              value = value.substring(0, value.length() - PACKAGE_INFO.length());
          }
          for (int i = 0, len = value.length(); i < len; i++) {
              char c = value.charAt(i);
              if (Character.isJavaIdentifierPart(c))
                  continue;
              if (extraAllowedCharacters.indexOf(c) >= 0)
                  continue;
              return false;
          }
          return true;
      }
docs: /* pp