fix(algorithm): record loop is not copied (#276)

Co-authored-by: 枫川 <guoshoujing.gsj@alibaba-inc.com>

Author: corgiboygsj

computer-algorithm/src/main/java/org/apache/hugegraph/computer/algorithm/path/rings/RingsDetection.java

@@ -83,7 +83,7 @@ public void compute(ComputationContext context, Vertex vertex,
                 if (isMin) {
                     sequence.add(id);
                     IdListList sequences = vertex.value();
-                    sequences.add(sequence);
+                    sequences.add(sequence.copy());
                 }
             } else {
                 boolean contains = false;

computer-test/src/main/java/org/apache/hugegraph/computer/algorithm/path/rings/RingsDetectionTest.java

@@ -21,6 +21,7 @@
 import java.util.List;
 import java.util.Map;
 import java.util.Set;
+import java.util.stream.Collectors;
 
 import org.apache.hugegraph.computer.algorithm.AlgorithmTestBase;
 import org.apache.hugegraph.computer.core.config.ComputerOptions;
@@ -124,6 +125,10 @@ private void assertResult(Id id, List<String> rings) {
             Set<String> expect = EXPECT_RINGS.getOrDefault(id.toString(),
                                                            new HashSet<>());
 
+            rings = rings.stream()
+                         .distinct()
+                         .collect(Collectors.toList());
+
             Assert.assertEquals(expect.size(), rings.size());
             for (String ring : rings) {
                 String error = "Expect: '" + ring + "' in " + expect;