feat: [analytics-data] add the EmptyFilter type to the Data API v1alpha

packages/google-analytics-data/protos/google/analytics/data/v1alpha/data.proto

@@ -201,6 +201,9 @@ message Filter {
 
     // A filter for between two values.
     BetweenFilter between_filter = 5;
+
+    // A filter for empty values such as "(not set)" and "" values.
+    EmptyFilter empty_filter = 6;
   }
 }
 
@@ -341,6 +344,9 @@ message BetweenFilter {
   NumericValue to_value = 2;
 }
 
+// Filter for empty values.
+message EmptyFilter {}
+
 // To represent a number.
 message NumericValue {
   // One of a numeric value
@@ -554,6 +560,16 @@ message ResponseMetaData {
   // Demographics and
   // Interests](https://support.google.com/analytics/answer/2799357).
   optional bool subject_to_thresholding = 8;
+
+  // If this report's results are
+  // [sampled](https://support.google.com/analytics/answer/13331292), this
+  // describes the percentage of events used in this report. One
+  // `samplingMetadatas` is populated for each date range. Each
+  // `samplingMetadatas` corresponds to a date range in the order that date
+  // ranges were specified in the request.
+  //
+  // However if the results are not sampled, this field will not be defined.
+  repeated SamplingMetadata sampling_metadatas = 9;
 }
 
 // Describes a dimension column in the report. Dimensions requested in a report
@@ -1472,8 +1488,8 @@ message FunnelResponseMetadata {
   // [sampled](https://support.google.com/analytics/answer/13331292), this
   // describes what percentage of events were used in this funnel report. One
   // `samplingMetadatas` is populated for each date range. Each
-  // `samplingMetadatas` corresponds to a date range in order that date ranges
-  // were specified in the request.
+  // `samplingMetadatas` corresponds to a date range in the order that date
+  // ranges were specified in the request.
   //
   // However if the results are not sampled, this field will not be defined.
   repeated SamplingMetadata sampling_metadatas = 1;