code: private static Reader loadInputStream(InputStream propertiesStream) throws IOException {
          StringBuilder buff = new StringBuilder();
  
          try (InputStreamReader isr = new InputStreamReader(propertiesStream, Charset.defaultCharset());
                  BufferedReader reader = new BufferedReader(isr)) {
              String line;
              while ((line = reader.readLine()) != null) {
                  buff.append(line).append("\n");
              }
          }
  
          return new StringReader(StrSubstitutor.replaceSystemProperties(buff.toString()));
      }
docs: Reads the {@link InputStream} and substitutes system properties.
  
  @return {@link Reader}