code: @SuppressWarnings("unchecked")
  	@Override
  	public final <T extends SolrDataQuery> T setFacetOptions(@Nullable FacetOptions facetOptions) {
  
  		if (facetOptions != null) {
  			Assert.isTrue(facetOptions.hasFacets(), "Cannot set facet options having neither fields nor queries.");
  		}
  		this.facetOptions = facetOptions;
  		return (T) this;
  	}
docs: /*
  (non-Javadoc)
  @see org.springframework.data.solr.core.query.FacetQuery#setFacetOptions(org.springframework.data.solr.core.query.FacetOptions)