code: protected void initTransformers() {
  		if (jsBlockTrans == null)
  			jsBlockTrans = new JSStringTransformer();
  		URLStringTransformer anchorTrans = new URLStringTransformer();
  		anchorTrans.setJsTransformer(jsBlockTrans);
  
  		transformers = new HashMap<String, StringTransformer>();
  		transformers.put("fw", new URLStringTransformer("fw_"));
  		transformers.put("if", new URLStringTransformer("if_"));
  		transformers.put("cs", new URLStringTransformer("cs_"));
  		transformers.put("js", new URLStringTransformer("js_"));
  		transformers.put("im", new URLStringTransformer("im_"));
  		transformers.put("oe", new URLStringTransformer("oe_"));
  		transformers.put("an", anchorTrans);
  		transformers.put("jb", jsBlockTrans);
  		transformers.put("ci", new InlineCSSStringTransformer());
  		transformers.put("mt", new MetaRefreshUrlStringTransformer());
  		transformers.put("ss", new SrcsetStringTransformer());
  		transformers.put("in", new RegexReplaceStringTransformer("^.*$", ""));
  		
  		if (customTransformers != null) {
  			transformers.putAll(customTransformers);
  			customTransformers = null;
  		}
  	}
docs: Initialize {@code StringTransformer}s, register them to
  {@code transformers} map by their name.