[fuzz] Added validation for secrets (#13543)

Signed-off-by: Zach <zasweq@google.com>

api/envoy/extensions/transport_sockets/tls/v3/secret.proto

@@ -12,6 +12,7 @@ import "udpa/annotations/migrate.proto";
 import "udpa/annotations/sensitive.proto";
 import "udpa/annotations/status.proto";
 import "udpa/annotations/versioning.proto";
+import "validate/validate.proto";
 
 option java_package = "io.envoyproxy.envoy.extensions.transport_sockets.tls.v3";
 option java_outer_classname = "SecretProto";
@@ -33,7 +34,10 @@ message SdsSecretConfig {
   // Name (FQDN, UUID, SPKI, SHA256, etc.) by which the secret can be uniquely referred to.
   // When both name and config are specified, then secret can be fetched and/or reloaded via
   // SDS. When only name is specified, then secret will be loaded from static resources.
-  string name = 1 [(udpa.annotations.field_migrate).oneof_promotion = "name_specifier"];
+  string name = 1 [
+    (validate.rules).string = {min_len: 1},
+    (udpa.annotations.field_migrate).oneof_promotion = "name_specifier"
+  ];
 
   // Resource locator for SDS. This is mutually exclusive to *name*.
   // [#not-implemented-hide:]