Allow an sdk member type not to provide a bp property

Bug: 181569894
Test: m nothing
Change-Id: I7e98f14cb377683457fba32fd05d6c614f78ffeb

android/sdk.go

@@ -380,6 +380,10 @@ type SdkMemberType interface {
 	// The name of the member type property on an sdk module.
 	SdkPropertyName() string
 
+	// RequiresBpProperty returns true if this member type requires its property to be usable within
+	// an Android.bp file.
+	RequiresBpProperty() bool
+
 	// True if the member type supports the sdk/sdk_snapshot, false otherwise.
 	UsableWithSdkAndSdkSnapshot() bool
 
@@ -452,7 +456,12 @@ type SdkMemberType interface {
 
 // Base type for SdkMemberType implementations.
 type SdkMemberTypeBase struct {
-	PropertyName    string
+	PropertyName string
+
+	// When set to true BpPropertyNotRequired indicates that the member type does not require the
+	// property to be specifiable in an Android.bp file.
+	BpPropertyNotRequired bool
+
 	SupportsSdk     bool
 	HostOsDependent bool
 
@@ -466,6 +475,10 @@ func (b *SdkMemberTypeBase) SdkPropertyName() string {
 	return b.PropertyName
 }
 
+func (b *SdkMemberTypeBase) RequiresBpProperty() bool {
+	return !b.BpPropertyNotRequired
+}
+
 func (b *SdkMemberTypeBase) UsableWithSdkAndSdkSnapshot() bool {
 	return b.SupportsSdk
 }