code: private String
        getPreprocessorDefinitions(final CommandLineCompilerConfiguration compilerConfig, final boolean isDebug) {
      final StringBuffer defines = new StringBuffer();
      final String[] args = compilerConfig.getPreArguments();
      for (final String arg : args) {
        if (arg.startsWith("/D")) {
          String macro = arg.substring(2);
          if (isDebug) {
            if (macro.equals("NDEBUG")) {
              macro = "_DEBUG";
            }
          } else {
            if (macro.equals("_DEBUG")) {
              macro = "NDEBUG";
            }
          }
          defines.append(macro);
          defines.append(";");
        }
      }
  
      if (defines.length() > 0) {
        defines.setLength(defines.length() - 1);
      }
      return defines.toString();
    }
docs: Get value of PreprocessorDefinitions property.
  
  @param compilerConfig
  compiler configuration.
  @param isDebug
  true if generating debug configuration.
  @return value of PreprocessorDefinitions property.