fixup: use md5

Signed-off-by: Todd Baert <todd.baert@dynatrace.com>

Author: toddbaert

docs/reference/flagd-ofrep.md

@@ -25,7 +25,7 @@ curl -X POST 'http://localhost:8016/ofrep/v1/evaluate/flags'
 
 ## HTTP Caching
 
-The bulk evaluation endpoint supports HTTP caching via ETags (SHA1-based). Clients can use the `If-None-Match` header with a previously received `ETag` to validate cached responses. When the response hasn't changed, the server returns `304 Not Modified` without a body, reducing bandwidth.
+The bulk evaluation endpoint supports HTTP caching via ETags (MD5-based). Clients can use the `If-None-Match` header with a previously received `ETag` to validate cached responses. When the response hasn't changed, the server returns `304 Not Modified` without a body, reducing bandwidth.
 
 ```shell
 curl -X POST 'http://localhost:8016/ofrep/v1/evaluate/flags' \

flagd/pkg/service/flag-evaluation/ofrep/handler.go

@@ -2,7 +2,7 @@ package ofrep
 
 import (
 	"context"
-	"crypto/sha1"
+	"crypto/md5"
 	"encoding/json"
 	"fmt"
 	"net/http"
@@ -194,7 +194,7 @@ func calculateETag(response ofrep.BulkEvaluationResponse) (string, []byte, error
 		return "", nil, fmt.Errorf("failed to marshal response for ETag calculation: %w", err)
 	}
 
-	hash := sha1.Sum(data)
+	hash := md5.Sum(data)
 	return fmt.Sprintf("\"%x\"", hash), data, nil
 }