[WIP] Awakeable IDs following the new ID scheme (#204)

Author: AhmedSoliman

sdk-core/src/main/java/dev/restate/sdk/core/Entries.java

@@ -19,6 +19,7 @@
 import java.util.function.Function;
 
 final class Entries {
+  static final String AWAKEABLE_IDENTIFIER_PREFIX = "prom_1";
 
   private Entries() {}
 

sdk-core/src/main/java/dev/restate/sdk/core/SyscallsImpl.java

@@ -265,7 +265,8 @@ public void awakeable(SyscallCallback<Map.Entry<String, DeferredResult<ByteStrin
                                         .rewind()));
 
                     return new AbstractMap.SimpleImmutableEntry<>(
-                        Base64.getUrlEncoder().encodeToString(awakeableId.toByteArray()),
+                        Entries.AWAKEABLE_IDENTIFIER_PREFIX
+                            + Base64.getUrlEncoder().encodeToString(awakeableId.toByteArray()),
                         deferredResult);
                   },
                   callback));

sdk-core/src/test/java/dev/restate/sdk/core/AwakeableIdTestSuite.java

@@ -42,7 +42,8 @@ public Stream<TestDefinition> definitions() {
     expectedAwakeableId.putInt(1);
     expectedAwakeableId.rewind();
     String base64ExpectedAwakeableId =
-        Base64.getUrlEncoder().encodeToString(expectedAwakeableId.array());
+        Entries.AWAKEABLE_IDENTIFIER_PREFIX
+            + Base64.getUrlEncoder().encodeToString(expectedAwakeableId.array());
 
     return Stream.of(
         testInvocation(this::returnAwakeableId, GreeterGrpc.getGreetMethod())