code: public ThymeleafEngineConfigBuilder<P> addDialect(final String prefix, final IDialect dialect) {
  		this.dialectsByPrefix().put(prefix, dialect);
  		return this;
  	}
docs: <p>
  Adds a new dialect for this template engine, using the specified prefix.
  </p>
  <p>
  This dialect will be added to the set of currently configured ones.
  </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 prefix
  the prefix that will be used for this dialect
  @param dialect
  the new {@link IDialect} to be added to the existing ones.
  @return this for fluent use