code: @Nonnull
    public static <KEYTYPE, VALUETYPE> String getImploded (final char cSepOuter,
                                                           final char cSepInner,
                                                           @Nullable final Map <KEYTYPE, VALUETYPE> aElements)
    {
      return getImplodedMapped (cSepOuter, cSepInner, aElements, String::valueOf, String::valueOf);
    }
docs: Get a concatenated String from all elements of the passed map, separated by
  the specified separator chars.
  
  @param cSepOuter
  The separator to use for separating the map entries.
  @param cSepInner
  The separator to use for separating the key from the value.
  @param aElements
  The map to convert. May be <code>null</code> or empty.
  @return The concatenated string.
  @param <KEYTYPE>
  Map key type
  @param <VALUETYPE>
  Map value type