add test

hutool-core/src/main/java/cn/hutool/core/collection/CollUtil.java

@@ -575,7 +575,7 @@ public class CollUtil {
 				}
 			}
 
-			if (false == foundCurrentElement) {
+			if (!foundCurrentElement) {
 				return false;
 			}
 		}
@@ -1805,7 +1805,7 @@ public class CollUtil {
 	 * @return 是否为空
 	 */
 	public static boolean isEmpty(Enumeration<?> enumeration) {
-		return null == enumeration || false == enumeration.hasMoreElements();
+		return null == enumeration || !enumeration.hasMoreElements();
 	}
 
 	/**
@@ -2336,7 +2336,7 @@ public class CollUtil {
 	 */
 	public static <T> List<T> addAllIfNotContains(List<T> list, List<T> otherList) {
 		for (T t : otherList) {
-			if (false == list.contains(t)) {
+			if (!list.contains(t)) {
 				list.add(t);
 			}
 		}
@@ -2841,7 +2841,7 @@ public class CollUtil {
 
 			@Override
 			public int hash32(T t) {
-				if (null == t || false == BeanUtil.isBean(t.getClass())) {
+				if (null == t || !BeanUtil.isBean(t.getClass())) {
 					// 非Bean放在同一子分组中
 					return 0;
 				}

hutool-core/src/test/java/cn/hutool/core/collection/CollUtilTest.java

@@ -9,6 +9,8 @@ import lombok.*;
 import org.junit.jupiter.api.Test;
 
 import java.util.*;
+import java.util.function.Function;
+import java.util.stream.Collectors;
 
 import static org.junit.jupiter.api.Assertions.*;
 
@@ -323,7 +325,7 @@ public class CollUtilTest {
 	public void filterTest2() {
 		final ArrayList<String> list = CollUtil.newArrayList("a", "b", "c");
 
-		final ArrayList<String> filtered = CollUtil.filter(list, t -> false == "a".equals(t));
+		final ArrayList<String> filtered = CollUtil.filter(list, t -> !"a".equals(t));
 
 		// 原地过滤
 		assertSame(list, filtered);
@@ -1532,4 +1534,21 @@ public class CollUtilTest {
 		assertNotNull(cat1);
 		assertEquals("cat", cat1.getName());
 	}
+
+	@Test
+	void issueIDBU9HTest(){
+		List<ToolTest> list = new ArrayList<>();
+		ToolTest t1 = new ToolTest("a");
+		ToolTest t2 = new ToolTest("b");
+		list.add(t1);
+		list.add(t2);
+		Map<String, ToolTest> map = list.stream().collect(Collectors.toMap(ToolTest::getName, Function.identity(), (k1, k2) -> k2));
+		CollectionUtil.subtract(map.keySet(), map.keySet());
+	}
+
+	@Data
+	@AllArgsConstructor
+	private static class ToolTest {
+		private String name;
+	}
 }