diff --git a/api/openapi-spec/swagger.json b/api/openapi-spec/swagger.json
index c1f60cb47f5..a6729a4bb3e 100644
--- a/api/openapi-spec/swagger.json
+++ b/api/openapi-spec/swagger.json
@@ -8899,9 +8899,6 @@
           "type": "array"
         }
       },
-      "required": [
-        "sources"
-      ],
       "type": "object"
     },
     "io.k8s.api.core.v1.QuobyteVolumeSource": {
diff --git a/staging/src/k8s.io/api/core/v1/generated.proto b/staging/src/k8s.io/api/core/v1/generated.proto
index 9b106528654..315ea803e84 100644
--- a/staging/src/k8s.io/api/core/v1/generated.proto
+++ b/staging/src/k8s.io/api/core/v1/generated.proto
@@ -3852,6 +3852,7 @@ message Probe {
 // Represents a projected volume source
 message ProjectedVolumeSource {
   // list of volume projections
+  // +optional
   repeated VolumeProjection sources = 1;
 
   // Mode bits used to set permissions on created files by default.
diff --git a/staging/src/k8s.io/api/core/v1/types.go b/staging/src/k8s.io/api/core/v1/types.go
index 2b99b967430..669c130aecb 100644
--- a/staging/src/k8s.io/api/core/v1/types.go
+++ b/staging/src/k8s.io/api/core/v1/types.go
@@ -1615,6 +1615,7 @@ type ServiceAccountTokenProjection struct {
 // Represents a projected volume source
 type ProjectedVolumeSource struct {
 	// list of volume projections
+	// +optional
 	Sources []VolumeProjection `json:"sources" protobuf:"bytes,1,rep,name=sources"`
 	// Mode bits used to set permissions on created files by default.
 	// Must be an octal value between 0000 and 0777 or a decimal value between 0 and 511.