code: @Nullable
    public static String getFileAsString (@Nullable final File aFile, @Nonnull final Charset aCharset)
    {
      return aFile == null ? null : StreamHelper.getAllBytesAsString (FileHelper.getInputStream (aFile), aCharset);
    }
docs: Get the content of the passed file as a string using the system line
  separator. Note: the last line does not end with the passed line separator.
  
  @param aFile
  The file to read. May be <code>null</code>.
  @param aCharset
  The character set to use. May not be <code>null</code>.
  @return <code>null</code> if the file does not exist, the content
  otherwise.