code: public static boolean isValidJson (@Nonnull final File aFile, @Nonnull final Charset aFallbackCharset)
    {
      return isValidJson (new FileSystemResource (aFile), aFallbackCharset);
    }
docs: Check if the passed File can be resembled to valid Json content. This is
  accomplished by fully parsing the Json file each time the method is called.
  This consumes <b>less memory</b> than calling any of the
  <code>read...</code> methods and checking for a non-<code>null</code>
  result.
  
  @param aFile
  The file to be parsed. May not be <code>null</code>.
  @param aFallbackCharset
  The charset to be used for reading the Json file in case no BOM is
  present. May not be <code>null</code>.
  @return <code>true</code> if the file can be parsed without error,
  <code>false</code> if not