JDBC warnings are not properly handled

Adding warnings individually results in redundant exceptions. See also TEIID-1829

This is a behavior change though since the resulting warnings on the client side will be held by the cause. Proper access would be:

//warning will be an instanceof TeiidSQLWarning to convey model/source information
SQLWarning warning = stmt.getWarnings();

while (warning != null) {
Exception e = warning.getCause();
if (cause instanceof SQLWarning) {
//childWarning should now be the head of the source warning chain
SQLWarning childWarning = (SQLWarning)cause;
while (childWarning != null)

{ //do something with childWarning childWarning = childWarning.getNextWarning(); }

}
warning = warning.getNextWarning();
}