profile: drop duplicate field in message Profile (#606)

* profile: drop duplicate field in message Profile

The message Profile contains two fields of type `opentelemetry.proto.common.v1.KeyValue`, `attribute_table` and `attributes`. Both fields are intended for the same use. Therefore drop the later one.

* fixup: add attribute_indices to message Profile

Signed-off-by: Florian Lehner <florian.lehner@elastic.co>

* fixup: move comment

Signed-off-by: Florian Lehner <florian.lehner@elastic.co>

---------

Signed-off-by: Florian Lehner <florian.lehner@elastic.co>
Co-authored-by: Liudmila Molkova <limolkova@microsoft.com>

opentelemetry/proto/profiles/v1development/profiles.proto

@@ -242,20 +242,6 @@ message Profile {
   // This field is required.
   bytes profile_id = 17;
 
-  // attributes is a collection of key/value pairs. Note, global attributes
-  // like server name can be set using the resource API. Examples of attributes:
-  //
-  //     "/http/user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36"
-  //     "/http/server_latency": 300
-  //     "abc.com/myattribute": true
-  //     "abc.com/score": 10.239
-  //
-  // The OpenTelemetry API specification further restricts the allowed value types:
-  // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/common/README.md#attribute
-  // Attribute keys MUST be unique (it is not allowed to have more than one
-  // attribute with the same key).
-  repeated opentelemetry.proto.common.v1.KeyValue attributes = 18;
-
   // dropped_attributes_count is the number of attributes that were discarded. Attributes
   // can be discarded because their keys are too long or because there are too many
   // attributes. If this value is 0, then no attributes were dropped.
@@ -271,6 +257,21 @@ message Profile {
   // The field is optional, however if it is present then equivalent converted data should be populated in other fields
   // of this message as far as is practicable.
   bytes original_payload = 21;
+
+  // References to attributes in attribute_table. [optional]
+  // It is a collection of key/value pairs. Note, global attributes
+  // like server name can be set using the resource API. Examples of attributes:
+  //
+  //     "/http/user_agent": "Mozilla/5.0 (Macintosh; Intel Mac OS X 10_14_2) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/71.0.3578.98 Safari/537.36"
+  //     "/http/server_latency": 300
+  //     "abc.com/myattribute": true
+  //     "abc.com/score": 10.239
+  //
+  // The OpenTelemetry API specification further restricts the allowed value types:
+  // https://github.com/open-telemetry/opentelemetry-specification/blob/main/specification/common/README.md#attribute
+  // Attribute keys MUST be unique (it is not allowed to have more than one
+  // attribute with the same key).
+  repeated int32 attribute_indices = 22;
 }
 
 // Represents a mapping between Attribute Keys and Units.