Addressed TODOs

src/main/proto/wfa/measurement/reporting/v2alpha/BUILD.bazel

@@ -420,14 +420,10 @@ kt_jvm_grpc_proto_library(
     deps = [":metric_calculation_specs_service_proto"],
 )
 
-# TODO(@kungfucraig): Figure out how to have a build rule for the operations service.
-# proto_library(
-#     name = "operations_service_proto",
-#     srcs = ["???"],
-#     strip_import_prefix = IMPORT_PREFIX,
-#     deps = [
-#     ],
-# )
+kt_jvm_grpc_proto_library(
+    name = "operations_service_kt_jvm_grpc_proto",
+    deps = ["@com_google_googleapis//google/longrunning:operations_proto",],
+)
 
 proto_library(
     name = "reports_service_proto",

src/main/proto/wfa/measurement/reporting/v2alpha/page.proto

@@ -250,7 +250,19 @@ message Page {
 
       // Display name of the component
       string display_name = 2 [(google.api.field_behavior) = IMMUTABLE];
-      // TODO(@kungfucraig): Phase II - Add support for Event Group summaries.
+
+      // Summary of an EventGroup entailed by the component
+      message EventGroupSummary {
+        string event_group = 1 [
+          (google.api.field_behavior) = REQUIRED,
+          (google.api.field_behavior) = IMMUTABLE,
+          (google.api.resource_reference) = {
+            type: "halo.wfanet.org/EventGroup"
+          }
+        ];
+        // TODO(@kungfucraig): Add EventGroup metadata once it has been
+        // formally encoded in the EventGroup.
+      }
     }
 
     // A summary of each component of the reporting_unit reported on