code: protected void replaceValue(Map<String, Object> content, String key, Object value) {
  		if (content.containsKey(key) && value != null) {
  			content.put(key, value);
  		}
  	}
docs: Replace the {@code value} for the specified key if the value is not {@code null}.
  @param content the content to expose
  @param key the property to replace
  @param value the new value