Add Beta feature gate for projected workspace

This commit adds the Beta feature gate for projected workspace in v1.

pkg/apis/pipeline/v1/workspace_validation.go

@@ -68,9 +68,16 @@ func (b *WorkspaceBinding) Validate(ctx context.Context) (errs *apis.FieldError)
 		return apis.ErrMissingField("secret.secretName")
 	}
 
+	// The projected workspace is only supported when the beta feature gate is enabled.
 	// For a Projected volume to work, you must provide at least one source.
 	if b.Projected != nil && len(b.Projected.Sources) == 0 {
-		return apis.ErrMissingField("projected.sources")
+		errs := version.ValidateEnabledAPIFields(ctx, "projected workspace type", config.BetaAPIFields).ViaField("workspaces")
+		if errs != nil {
+			return errs
+		}
+		if len(b.Projected.Sources) == 0 {
+			return apis.ErrMissingField("projected.sources")
+		}
 	}
 
 	// The csi workspace is only supported when the alpha feature gate is enabled.

pkg/apis/pipeline/v1/workspace_validation_test.go

@@ -102,6 +102,7 @@ func TestWorkspaceBindingValidateValid(t *testing.T) {
 				}},
 			},
 		},
+		wc: config.EnableBetaAPIFields,
 	}, {
 		name: "Valid csi",
 		binding: &v1.WorkspaceBinding{
@@ -165,12 +166,19 @@ func TestWorkspaceBindingValidateInvalid(t *testing.T) {
 			Name:   "beth",
 			Secret: &corev1.SecretVolumeSource{},
 		},
+	}, {
+		name: "projected workspace should be disallowed without beta feature gate",
+		binding: &v1.WorkspaceBinding{
+			Name:      "beth",
+			Projected: &corev1.ProjectedVolumeSource{},
+		},
 	}, {
 		name: "Provide projected without sources",
 		binding: &v1.WorkspaceBinding{
 			Name:      "beth",
 			Projected: &corev1.ProjectedVolumeSource{},
 		},
+		wc: config.EnableBetaAPIFields,
 	}, {
 		name: "csi workspace should be disallowed without alpha feature gate",
 		binding: &v1.WorkspaceBinding{