code: public static boolean isValidImportString(String s) {
          if (s.equals("*"))
              return true;
  
          boolean valid = true;
          String t = s;
          int index = t.indexOf('*');
  
          if (index != -1) {
              // '*' must be last character...
              if (index == t.length() -1) {
                  // ... any and preceding character must be '.'
                  if ( index-1 >= 0 ) {
                      valid = t.charAt(index-1) == '.';
                      // Strip off ".*$" for identifier checks
                      t = t.substring(0, t.length()-2);
                  }
              } else
                  return false;
          }
  
          // Verify string is off the form (javaId \.)+ or javaId
          if (valid) {
              String[] javaIds = t.split("\\.", t.length()+2);
              for(String javaId: javaIds)
                  valid &= SourceVersion.isIdentifier(javaId);
          }
          return valid;
      }
docs: Return true if the argument string is a valid import-style
  string specifying claimed annotations; return false otherwise.