code: protected void doBody(E element, CaptureLevel captureLevel) throws JspException, IOException {
  		JspFragment body = getJspBody();
  		if(body != null) {
  			if(captureLevel == CaptureLevel.BODY) {
  				final PageContext pageContext = (PageContext)getJspContext();
  				// Invoke tag body, capturing output
  				BufferWriter capturedOut = AutoEncodingBufferedTag.newBufferWriter(pageContext.getRequest());
  				try {
  					body.invoke(capturedOut);
  				} finally {
  					capturedOut.close();
  				}
  				element.setBody(capturedOut.getResult().trim());
  			} else if(captureLevel == CaptureLevel.META) {
  				// Invoke body for any meta data, but discard any output
  				body.invoke(NullWriter.getInstance());
  			} else {
  				throw new AssertionError();
  			}
  		}
  	}
docs: This is only called for captureLevel >= META.