private void renderPassThroughAttributes(FacesContext context, UIComponent component) throws IOException {
        Map<String, Object> passthroughAttributes = component.getPassThroughAttributes(false);

        if (passthroughAttributes != null && !passthroughAttributes.isEmpty()) {
            ResponseWriter writer = context.getResponseWriter();

            for (Map.Entry<String, Object> attribute : passthroughAttributes.entrySet()) {
                Object attributeValue = attribute.getValue();
                if (attributeValue != null) {
                    String value = null;

                    if (attributeValue instanceof ValueExpression) {
                        Object expressionValue = ((ValueExpression) attributeValue).getValue(context.getELContext());
                        if (expressionValue != null) {
                            value = expressionValue.toString();
                        }
                    }
                    else {
                        value = attributeValue.toString();
                    }

                    if (value != null) {
                        writer.writeAttribute(attribute.getKey(), value, null);
                    }
                }
            }
        }
    }
Logs a WARN log message in ProjectStage == DEVELOPMENT.
@param context the FacesContext
@param clazz the class or object for which the log is generated
@param message the message to log
primefaces/src/main/java/org/primefaces/renderkit/CoreRenderer.java