Remove Exemplars from Histogram, will be added later for all points (#193)

Signed-off-by: Bogdan Drutu <bogdandrutu@gmail.com>

Author: bogdandrutu

opentelemetry/proto/metrics/v1/metrics.proto

@@ -430,45 +430,14 @@ message HistogramDataPoint {
   // a histogram is provided.
   double sum = 5;
 
-  // Bucket contains values for a bucket.
-  message Bucket {
-    // The number of values in each bucket of the histogram, as described by
-    // bucket_options.
-    uint64 count = 1;
-
-    // Exemplars are example points that may be used to annotate aggregated
-    // Histogram values. They are metadata that gives information about a
-    // particular value added to a Histogram bucket.
-    message Exemplar {
-      // Value of the exemplar point. It determines which bucket the exemplar belongs to.
-      // If bucket_options define bounds for this bucket then this value must be within
-      // the defined bounds.
-      double value = 1;
-
-      // time_unix_nano is the moment when this exemplar was recorded.
-      // Value is UNIX Epoch time in nanoseconds since 00:00:00 UTC on 1 January 1970.
-      fixed64 time_unix_nano = 2;
-
-      // exemplar_attachments are contextual information about the example value.
-      // Keys in this list must be unique.
-      repeated opentelemetry.proto.common.v1.StringKeyValue attachments = 3;
-    }
-
-    // exemplar is an optional representative value of the bucket.
-    Exemplar exemplar = 2;
-  }
-
-  // buckets is an optional field contains the values of histogram for each bucket.
-  //
-  // The sum of the values in the buckets "count" field must equal the value in the count field.
+  // bucket_counts is an optional field contains the count values of histogram
+  // for each bucket.
   //
-  // The number of elements in buckets array must be by one greater than the
-  // number of elements in bucket_bounds array.
+  // The sum of the bucket_counts must equal the value in the count field.
   //
-  // Note: if HistogramDataPoint.bucket_options defines bucket bounds then this field
-  // must also be present and number of elements in this field must be equal to the
-  // number of buckets defined by bucket_options.
-  repeated Bucket buckets = 6;
+  // The number of elements in bucket_counts array must be by one greater than
+  // the number of elements in explicit_bounds array.
+  repeated uint64 bucket_counts = 6;
 
   // A histogram may optionally contain the distribution of the values in the population.
   // In that case one of the option fields below and "buckets" field both must be defined.