public boolean isEnabled() {
        return enabled;
    }
Returns {@code true} if this filter should <em>generally</em><b>*</b> execute for any request,
{@code false} if it should let the request/response pass through immediately to the next
element in the {@link FilterChain}.  The default value is {@code true}, as most filters would inherently need
to execute when configured.
<p/>
<b>*</b> This configuration property is for general configuration for any request that comes through
the filter.  The
{@link #isEnabled(javax.servlet.ServletRequest, javax.servlet.ServletResponse) isEnabled(request,response)}
method actually determines whether or not if the filter is enabled based on the current request.

@return {@code true} if this filter should <em>generally</em> execute, {@code false} if it should let the
request/response pass through immediately to the next element in the {@link FilterChain}.
@since 1.2
web/src/main/java/org/apache/shiro/web/servlet/OncePerRequestFilter.java