[DCOS-44701] adding interface for debug endpoints (#2791)

* adding interface for debug endpoints

* newline cleanup

sdk/debug/DebugEndpoint.java

@@ -0,0 +1,21 @@
+package com.mesosphere.sdk.debug;
+import javax.ws.rs.QueryParam;
+import javax.ws.rs.core.Response;
+/**
+ * Interface for all debug endpoints.
+ */
+public interface DebugEndpoint {
+  /**
+   * Called to retun JSON response of requested endpoint.
+   * @param plan (optional) Plan to drill down on.
+   * @param phase (optional) Phase to drill down on.
+   * @param step (optional) Step to drill down on.
+   * @param sync (optional) Poll backend State-Stores.
+   * @return JSON response of the requested debug endpoint.
+   */
+  public Response getJson(
+      @QueryParam("plan") String plan,
+      @QueryParam("phase") String phase,
+      @QueryParam("step") String step,
+      @QueryParam("sync") boolean sync);
+}