HBASE-27117 Update the method comments for RegionServerAccounting (#4532)

Author: tomscut

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/MemStoreFlusher.java

@@ -428,14 +428,14 @@ private boolean refreshStoreFilesAndReclaimMemory(Region region) {
   }
 
   /**
-   * Return true if global memory usage is above the high watermark
+   * Return the FlushType if global memory usage is above the high watermark
    */
   private FlushType isAboveHighWaterMark() {
     return server.getRegionServerAccounting().isAboveHighWaterMark();
   }
 
   /**
-   * Return true if we're above the low watermark
+   * Return the FlushType if we're above the low watermark
    */
   private FlushType isAboveLowWaterMark() {
     return server.getRegionServerAccounting().isAboveLowWaterMark();

hbase-server/src/main/java/org/apache/hadoop/hbase/regionserver/RegionServerAccounting.java

@@ -161,8 +161,8 @@ public void decGlobalMemStoreSize(long dataSizeDelta, long heapSizeDelta, long o
   }
 
   /**
-   * Return true if we are above the memstore high water mark
-   * @return the flushtype
+   * Return the FlushType if we are above the memstore high water mark
+   * @return the FlushType
    */
   public FlushType isAboveHighWaterMark() {
     // for onheap memstore we check if the global memstore size and the
@@ -193,7 +193,8 @@ public FlushType isAboveHighWaterMark() {
   }
 
   /**
-   * Return true if we're above the low watermark
+   * Return the FlushType if we're above the low watermark
+   * @return the FlushType
    */
   public FlushType isAboveLowWaterMark() {
     // for onheap memstore we check if the global memstore size and the