Clears the "static" and persistent caches.
public function flush() {
$this->fieldMap = NULL;
$this->fieldsById = array();
$this->fieldIdsByName = array();
$this->loadedAllFields = FALSE;
$this->unknownFields = array();
$this->bundleInstances = array();
$this->loadedAllInstances = FALSE;
$this->emptyBundles = array();
$this->bundleExtraFields = array();
cache_clear_all('field_info:', 'cache_field', TRUE);
}