SGF-821 - Adapt tests to AssertJ 3.12.0.

src/test/java/org/springframework/data/gemfire/domain/support/AbstractSliceSupportTests.java

@@ -18,6 +18,7 @@
 package org.springframework.data.gemfire.domain.support;
 
 import static org.assertj.core.api.Assertions.assertThat;
+import static org.mockito.Mockito.atLeastOnce;
 import static org.mockito.Mockito.doReturn;
 import static org.mockito.Mockito.mock;
 import static org.mockito.Mockito.times;
@@ -153,7 +154,7 @@ public class AbstractSliceSupportTests {
 	@SuppressWarnings("unchecked")
 	public void iteratorWithContent() {
 		doReturn(Arrays.asList(1, 2, 3)).when(mockSlice).getContent();
-		assertThat(mockSlice.iterator()).contains(1, 2, 3);
-		verify(mockSlice, times(1)).getContent();
+		assertThat((Iterable) () -> mockSlice.iterator()).contains(1, 2, 3);
+		verify(mockSlice, atLeastOnce()).getContent();
 	}
 }

src/test/java/org/springframework/data/gemfire/util/CollectionUtilsUnitTests.java

@@ -439,7 +439,7 @@ public class CollectionUtilsUnitTests {
 		Iterator<?> iterator = CollectionUtils.nullSafeIterator(null);
 
 		assertThat(iterator).isNotNull();
-		assertThat(iterator).isEmpty();
+		assertThat(iterator).isExhausted();
 	}
 
 	@Test