title: get rid of unwanted params in grails pagination
body: <p>I have a search webpage where user's can filter the search results by a person's ethnicity, as a checkbox group.  There are 12 'ethnicity' checkboxes.  The params get passed into g:paginate as the following, so that the user can page through the results and preserve what was checked in the ethnicity checkboxes:</p>
  
  <pre><code>&lt;g:paginate controller="search" action="list" total="${resultCount}" params="${params}"/&gt;
  </code></pre>
  
  <p>What gets output for the links includes a bunch of unnecessary data for each built URL:</p>
  
  <pre><code>&lt;a href="/myapp/search/list?_ethnicity=&amp;amp;_ethnicity=&amp;amp;_ethnicity=&amp;amp;_ethnicity=&amp;amp;_ethnicity=&amp;amp;_ethnicity=&amp;amp;_ethnicity=&amp;amp;_ethnicity=&amp;amp;_ethnicity=&amp;amp;_gender=&amp;amp;_gender=&amp;amp;_gender=&amp;amp;accountType=2&amp;amp;ethnicity=1&amp;amp;ethnicity=5&amp;amp;max=3&amp;amp;offset=3" class="step"&gt;2&lt;/a&gt;
  </code></pre>
  
  <p>I'd like the pagination link URLs to be output without all the extra _ethnicity variables that get passed back in the original search post:</p>
  
  <pre><code>&lt;a href="/myapp/search/list?accountType=2&amp;amp;ethnicity=1&amp;amp;ethnicity=5&amp;amp;max=3&amp;amp;offset=3" class="step"&gt;2&lt;/a&gt;
  </code></pre>
  
  <p>How can I get the params into the paginate tag without all the extra unnecessary fields?  Functionally it works, but the URLs for the paginate get requests are too long and look hideous.</p>