### Question:
FlowCacheKeys { public static FlowCacheKeysBuilder builder(){ return new FlowCacheKeysBuilder(); } private  FlowCacheKeys(FlowCacheKeysBuilder builder); String getValue(); static FlowCacheKeysBuilder builder();  }### Answer:
@Test public void testBuilder() { FlowCacheKeys.FlowCacheKeysBuilder builder = null; try { builder = FlowCacheKeys.builder(); } catch (Exception e) { fail("Exception thrown: " + e.getMessage()); } assertNotNull(builder); }