### Question:
URLParameterDecoder implements IDecoder <String, String> { @Nullable public String getDecoded (@Nullable final String sInput) { return URLHelper.urlDecodeOrNull (sInput, m_aCharset); } URLParameterDecoder(@Nonnull final Charset aCharset); @Nonnull final Charset getCharset(); @Nullable String getDecoded(@Nullable final String sInput);  }### Answer:
@Test public void testDecode () { final URLParameterDecoder aPD = new URLParameterDecoder (StandardCharsets.ISO_8859_1); assertEquals ("a b c", aPD.getDecoded ("a%20b+c")); assertEquals ("a b c:d", aPD.getDecoded ("a%20b+c%3Ad")); assertEquals ("a b c:d", aPD.getDecoded ("a%20b+c%3ad")); }