Add HCR mechanisms. (microsoft#130)

* Add HCR mechanisms.

* Update from code review.

* Fix access level

Author: yaohaizh

com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/adapter/IHotCodeReplaceProvider.java

@@ -12,8 +12,8 @@
 package com.microsoft.java.debug.core.adapter;
 
 import java.util.List;
-import java.util.concurrent.CompletableFuture;
+import java.util.function.Consumer;
 
 public interface IHotCodeReplaceProvider extends IProvider {
-    CompletableFuture<List<String>> redefineClasses();
+    void onClassRedefined(Consumer<List<String>> consumer);
 }

com.microsoft.java.debug.core/src/main/java/com/microsoft/java/debug/core/adapter/handler/SetBreakpointsRequestHandler.java

@@ -45,13 +45,25 @@ public class SetBreakpointsRequestHandler implements IDebugRequestHandler {
 
     private BreakpointManager manager = new BreakpointManager();
 
+    private boolean isHcrInitialized = false;
+
     @Override
     public List<Command> getTargetCommands() {
         return Arrays.asList(Command.SETBREAKPOINTS);
     }
 
     @Override
     public CompletableFuture<Response> handle(Command command, Arguments arguments, Response response, IDebugAdapterContext context) {
+        // TODO: This part logic should be part of post launching handler.
+        //       Add post launch logic and move the reinstall breakpoints logic there.
+        if (!isHcrInitialized) {
+            IHotCodeReplaceProvider hcrProvider = context.getProvider(IHotCodeReplaceProvider.class);
+            hcrProvider.onClassRedefined((typenames) -> {
+                this.reinstallBreakpoints(context, typenames);
+            });
+            isHcrInitialized = true;
+        }
+
         if (context.getDebugSession() == null) {
             return AdapterUtils.createAsyncErrorResponse(response, ErrorCode.EMPTY_DEBUG_SESSION, "Empty debug session.");
         }
@@ -85,11 +97,6 @@ public CompletableFuture<Response> handle(Command command, Arguments arguments,
                         String.format("Failed to setBreakpoint. Reason: '%s' is an invalid path.", bpArguments.source.path));
         }
 
-        if (bpArguments.sourceModified) {
-            IHotCodeReplaceProvider hcrProvider = context.getProvider(IHotCodeReplaceProvider.class);
-            hcrProvider.redefineClasses().thenAcceptAsync((List<String> result) -> reinstallBreakpoints(context, result));
-        }
-
         try {
             List<Types.Breakpoint> res = new ArrayList<>();
             IBreakpoint[] toAdds = this.convertClientBreakpointsToDebugger(sourcePath, bpArguments.breakpoints, context);