public Optional<String> getNodeName(String nodeId) {
        return nodeNameCache.getUnchecked(nodeId);
    }
@Test
    public void getNodeNameReturnsEmptyOptionalIfNodeIdIsInvalid() {
        when(cluster.nodeIdToName("node_id")).thenReturn(Optional.empty());
        assertThat(nodeInfoCache.getNodeName("node_id")).isEmpty();
    }