public void clearWarnings() {
        sqlwarn = null;
    }
Clears all the warnings reporeted for the <code>CachedRowSetImpl</code>
object. After a call to this method, the <code>getWarnings</code> method
returns <code>null</code> until a new warning is reported for this
<code>CachedRowSetImpl</code> object.
src/main/java/org/replicadb/rowset/sun/rowset/CachedRowSetImpl.java