fix typo (#133)

Author: YangKian

client/src/main/java/io/hstream/Subscription.java

@@ -15,7 +15,7 @@ public class Subscription {
   private SubscriptionOffset offset;
 
   public enum SubscriptionOffset {
-    EARLEST,
+    EARLIEST,
     LATEST,
   }
 

client/src/main/java/io/hstream/util/GrpcUtils.java

@@ -29,7 +29,7 @@ public static RecordId recordIdToGrpc(String recordId) {
 
   public static SpecialOffset subscriptionOffsetToGrpc(Subscription.SubscriptionOffset offset) {
     switch (offset) {
-      case EARLEST:
+      case EARLIEST:
         return io.hstream.internal.SpecialOffset.EARLIEST;
       case LATEST:
         return io.hstream.internal.SpecialOffset.LATEST;
@@ -41,7 +41,7 @@ public static SpecialOffset subscriptionOffsetToGrpc(Subscription.SubscriptionOf
   public static Subscription.SubscriptionOffset subscriptionOffsetFromGrpc(SpecialOffset offset) {
     switch (offset) {
       case EARLIEST:
-        return Subscription.SubscriptionOffset.EARLEST;
+        return Subscription.SubscriptionOffset.EARLIEST;
       case LATEST:
         return Subscription.SubscriptionOffset.LATEST;
       default: