HBASE-28334 Add comment around erasure coding policy in DEFAULT_VALUE map (#5662)

Signed-off-by: Bryan Beaudreault <bbeaudreault@apache.org>

Author: nirdosh0110

hbase-client/src/main/java/org/apache/hadoop/hbase/client/TableDescriptorBuilder.java

@@ -242,6 +242,7 @@ public class TableDescriptorBuilder {
     DEFAULT_VALUES.put(DURABILITY, DEFAULT_DURABLITY.name()); // use the enum name
     DEFAULT_VALUES.put(REGION_REPLICATION, String.valueOf(DEFAULT_REGION_REPLICATION));
     DEFAULT_VALUES.put(PRIORITY, String.valueOf(DEFAULT_PRIORITY));
+    // Setting ERASURE_CODING_POLICY to NULL so that it is not considered as metadata
     DEFAULT_VALUES.put(ERASURE_CODING_POLICY, String.valueOf(DEFAULT_ERASURE_CODING_POLICY));
     DEFAULT_VALUES.keySet().stream().map(s -> new Bytes(Bytes.toBytes(s)))
       .forEach(RESERVED_KEYWORDS::add);