code: protected Map<String, String> getElementAttributes() {
          // Preserve order of attributes
          Map<String, String> attrs = new HashMap<>();
  
          if (this.getVolume() != null) {
              attrs.put("volume", this.getVolume());
          }
          if (this.getRate() != null) {
              attrs.put("rate", this.getRate());
          }
          if (this.getPitch() != null) {
              attrs.put("pitch", this.getPitch());
          }
  
          return attrs;
      }
docs: Attributes to set on the generated XML element
  
  @return A Map of attribute keys to values