wrong-content-type-ajax-excecute-all-reproducer (reproducer for Mojarra #4358)

Steps to reproduce:

1. Clone the wrong-content-type-ajax-excecute-all-reproducer project:

   git clone https://github.com/stiemannkj1/wrong-content-type-ajax-excecute-all-reproducer.git
   

2. Build the project:

   cd wrong-content-type-ajax-excecute-all-reproducer && mvn clean package
   

3. Deploy the project to Tomcat:

   cp target/*.war $TOMCAT_HOME/webapps/wrong-content-type-ajax-excecute-all-reproducer.war
   

4. Navigate to the deployed webapp at http://localhost:8080/wrong-content-type-ajax-excecute-all-reproducer/.

5. Note that the External Context Calls: show that setResponseContentType("text/html") was correctly called before the first call to getResponseOutputWriter().

6. Click the Execute (default) Ajax Request button.

7. Note that the External Context Calls: show that setResponseContentType("text/xml") was correctly called before the first call to getResponseOutputWriter().

8. Click the Execute @all Ajax Request button.

If the bug still exists, the External Context Calls: will show that setResponseContentType("text/html") was incorrectly called before the first call to getResponseOutputWriter()`.

If the bug is fixed, the External Context Calls: will show that setResponseContentType("text/xml") was called immediately before the first call to getResponseOutputWriter().

Additional Information:

The Servlet 3.1 Specification states (in section 5.5 Internationalization):

The setCharacterEncoding, setContentType, and setLocale methods can be called repeatedly to change the character encoding. Calls made after the servlet response’s getWriter method has been called or after the response is committed have no effect on the character encoding.

Therefore, before the first call to externalContext.getResponseOutputWriter(), externalContext.setResponseContentType() must be called with the correct content type.

Although this bug does not seem to break anything, that's likely because servlet implementations do not perfectly implement the requirements of the servlet spec. This does cause issues in Servlet and Portlet Containers (such as Liferay) that correctly implement their respective specs.