HBASE-26185 Return mutable list in AssignmentManager#getExcludedServersForSystemTable (#3577)

shahrs87 · virajjasani · commit 3ee40e001fec · 2021-08-12T13:48:48.000+05:30
Signed-off-by: Viraj Jasani &lt;vjasani@apache.org&gt;
diff --git a/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java b/hbase-server/src/main/java/org/apache/hadoop/hbase/master/assignment/AssignmentManager.java
@@ -2281,15 +2281,15 @@ public List<ServerName> getExcludedServersForSystemTable() {
       .map(s->new Pair<>(s, master.getRegionServerVersion(s)))
       .collect(Collectors.toList());
     if (serverList.isEmpty()) {
-      return Collections.emptyList();
+      return new ArrayList<>();
     }
     String highestVersion = Collections.max(serverList,
       (o1, o2) -> VersionInfo.compareVersion(o1.getSecond(), o2.getSecond())).getSecond();
     if (!DEFAULT_MIN_VERSION_MOVE_SYS_TABLES_CONFIG.equals(minVersionToMoveSysTables)) {
       int comparedValue = VersionInfo.compareVersion(minVersionToMoveSysTables,
         highestVersion);
       if (comparedValue > 0) {
-        return Collections.emptyList();
+        return new ArrayList<>();
       }
     }
     return serverList.stream()

Original file line number	Diff line number	Diff line change
`@@ -2281,15 +2281,15 @@ public List<ServerName> getExcludedServersForSystemTable() {`
`2281`	`2281`	`.map(s->new Pair<>(s, master.getRegionServerVersion(s)))`
`2282`	`2282`	`.collect(Collectors.toList());`
`2283`	`2283`	`if (serverList.isEmpty()) {`
`2284`		`- return Collections.emptyList();`
	`2284`	`+ return new ArrayList<>();`
`2285`	`2285`	`}`
`2286`	`2286`	`String highestVersion = Collections.max(serverList,`
`2287`	`2287`	`(o1, o2) -> VersionInfo.compareVersion(o1.getSecond(), o2.getSecond())).getSecond();`
`2288`	`2288`	`if (!DEFAULT_MIN_VERSION_MOVE_SYS_TABLES_CONFIG.equals(minVersionToMoveSysTables)) {`
`2289`	`2289`	`int comparedValue = VersionInfo.compareVersion(minVersionToMoveSysTables,`
`2290`	`2290`	`highestVersion);`
`2291`	`2291`	`if (comparedValue > 0) {`
`2292`		`- return Collections.emptyList();`
	`2292`	`+ return new ArrayList<>();`
`2293`	`2293`	`}`
`2294`	`2294`	`}`
`2295`	`2295`	`return serverList.stream()`