feat: Mark all fields Optional for ContainerImageSignagure proto

PiperOrigin-RevId: 553825354

google/cloud/confidentialcomputing/v1/BUILD.bazel

@@ -318,7 +318,6 @@ load(
 
 csharp_proto_library(
     name = "confidentialcomputing_csharp_proto",
-    extra_opts = [],
     deps = [":confidentialcomputing_proto"],
 )
 

google/cloud/confidentialcomputing/v1/service.proto

@@ -231,23 +231,23 @@ message SignedEntity {
 // ContainerImageSignature holds necessary metadata to verify a container image
 // signature.
 message ContainerImageSignature {
-  // Required. The binary signature payload following the SimpleSigning format
+  // Optional. The binary signature payload following the SimpleSigning format
   // https://github.com/sigstore/cosign/blob/main/specs/SIGNATURE_SPEC.md#simple-signing.
   // This payload includes the container image digest.
-  bytes payload = 1 [(google.api.field_behavior) = REQUIRED];
+  bytes payload = 1 [(google.api.field_behavior) = OPTIONAL];
 
-  // Required. A signature over the payload.
+  // Optional. A signature over the payload.
   // The container image digest is incorporated into the signature as follows:
   // 1. Generate a SimpleSigning format payload that includes the container
   // image digest.
   // 2. Generate a signature over SHA256 digest of the payload.
   // The signature generation process can be represented as follows:
   // `Sign(sha256(SimpleSigningPayload(sha256(Image Manifest))))`
-  bytes signature = 2 [(google.api.field_behavior) = REQUIRED];
+  bytes signature = 2 [(google.api.field_behavior) = OPTIONAL];
 
-  // Required. An associated public key used to verify the signature.
-  bytes public_key = 3 [(google.api.field_behavior) = REQUIRED];
+  // Optional. Reserved for future use.
+  bytes public_key = 3 [(google.api.field_behavior) = OPTIONAL];
 
-  // Required. The algorithm used to produce the container image signature.
-  SigningAlgorithm sig_alg = 4 [(google.api.field_behavior) = REQUIRED];
+  // Optional. Reserved for future use.
+  SigningAlgorithm sig_alg = 4 [(google.api.field_behavior) = OPTIONAL];
 }