code: private void convertPropertiesMap(CompilerOptions options) {
      @SuppressWarnings("unchecked")
      Map<String, Object> props = getProject().getProperties();
      for (Map.Entry<String, Object> entry : props.entrySet()) {
        String key = entry.getKey();
        Object value = entry.getValue();
  
        if (key.startsWith(replacePropertiesPrefix)) {
          key = key.substring(replacePropertiesPrefix.length());
  
          if (!setDefine(options, key, value)) {
            log("Unexpected property value for key=" + key + "; value=" + value);
          }
        }
      }
    }
docs: Converts project properties beginning with the replacement prefix
  into Compiler {@code @define} replacements.
  
  @param options