code: public ThymeleafEngineConfigBuilder<P> setDialectsByPrefix(final Map<String, IDialect> dialects) {
  		dialectsByPrefix().clear();
  		dialectsByPrefix().putAll(dialects);
  		return this;
  	}
docs: <p>
  Sets a new set of dialects for this template engine, referenced by the
  prefixes they will be using.
  </p>
  <p>
  This operation can only be executed before processing templates for the
  first time. Once a template is processed, the template engine is
  considered to be <i>initialized</i>, and from then on any attempt to
  change its configuration will result in an exception.
  </p>
  
  @param dialects
  the new map of {@link IDialect} objects to be used, referenced
  by their prefixes.
  @return this for fluent use