public boolean isPostOnlyLogout() {
        return postOnlyLogout;
    }
Due to browser pre-fetching, using a GET requests for logout my cause a user to be logged accidentally, for example:
out while typing in an address bar.  If <code>postOnlyLogout</code> is <code>true</code>. Only POST requests will cause
a logout to occur.

@return Returns true if POST only logout is enabled
web/src/main/java/org/apache/shiro/web/filter/authc/LogoutFilter.java