public List<String> getVariables() {
    List<String> variables = new ArrayList<>();
    for (Template template : this.values) {
      variables.addAll(template.getVariables());
    }
    return Collections.unmodifiableList(variables);
  }
Create a new Header Template.

@param name of the header
@param values of the header
@param charset for the header
@param literal indicator. Will treat all values as literals instead of possible expressions.
core/src/main/java/feign/template/HeaderTemplate.java