HDFS-16321. Fix invalid config in TestAvailableSpaceRackFaultTolerantBPP (#3655). Contributed by guo.

Signed-off-by: Ayush Saxena <ayushsaxena@apache.org>

hadoop-hdfs-project/hadoop-hdfs/src/test/java/org/apache/hadoop/hdfs/server/blockmanagement/TestAvailableSpaceRackFaultTolerantBPP.java

@@ -65,7 +65,7 @@ public class TestAvailableSpaceRackFaultTolerantBPP {
   public static void setupCluster() throws Exception {
     conf = new HdfsConfiguration();
     conf.setFloat(
-        DFSConfigKeys.DFS_NAMENODE_AVAILABLE_SPACE_BLOCK_PLACEMENT_POLICY_BALANCED_SPACE_PREFERENCE_FRACTION_KEY,
+        DFSConfigKeys.DFS_NAMENODE_AVAILABLE_SPACE_RACK_FAULT_TOLERANT_BLOCK_PLACEMENT_POLICY_BALANCED_SPACE_PREFERENCE_FRACTION_KEY,
         0.6f);
     String[] racks = new String[NUM_RACKS];
     for (int i = 0; i < NUM_RACKS; i++) {