Fix build breakages when WITHOUT_CHECK_API=true

Bug: 158578354
Test: export WITHOUT_CHECK_API=true
      m checkbuild
Change-Id: I7b5fff40b870c9d754f779ff1c3314bac7e42440
Merged-In: I7b5fff40b870c9d754f779ff1c3314bac7e42440
diff --git a/java/droiddoc.go b/java/droiddoc.go
index d6bff95..a24d44b 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -1414,7 +1414,7 @@
 }
 
 func (d *Droidstubs) apiToXmlFlags(ctx android.ModuleContext, cmd *android.RuleBuilderCommand) {
-	if Bool(d.properties.Jdiff_enabled) && !ctx.Config().IsPdkBuild() {
+	if Bool(d.properties.Jdiff_enabled) && !ctx.Config().IsPdkBuild() && d.apiFile != nil {
 		if d.apiFile.String() == "" {
 			ctx.ModuleErrorf("API signature file has to be specified in Metalava when jdiff is enabled.")
 		}
@@ -1835,13 +1835,19 @@
 			Flag("-XDignore.symbol.file").
 			FlagWithArg("-doclet ", "jdiff.JDiff").
 			FlagWithInput("-docletpath ", jdiff).
-			Flag("-quiet").
-			FlagWithArg("-newapi ", strings.TrimSuffix(d.apiXmlFile.Base(), d.apiXmlFile.Ext())).
-			FlagWithArg("-newapidir ", filepath.Dir(d.apiXmlFile.String())).
-			Implicit(d.apiXmlFile).
-			FlagWithArg("-oldapi ", strings.TrimSuffix(d.lastReleasedApiXmlFile.Base(), d.lastReleasedApiXmlFile.Ext())).
-			FlagWithArg("-oldapidir ", filepath.Dir(d.lastReleasedApiXmlFile.String())).
-			Implicit(d.lastReleasedApiXmlFile)
+			Flag("-quiet")
+
+		if d.apiXmlFile != nil {
+			cmd.FlagWithArg("-newapi ", strings.TrimSuffix(d.apiXmlFile.Base(), d.apiXmlFile.Ext())).
+				FlagWithArg("-newapidir ", filepath.Dir(d.apiXmlFile.String())).
+				Implicit(d.apiXmlFile)
+		}
+
+		if d.lastReleasedApiXmlFile != nil {
+			cmd.FlagWithArg("-oldapi ", strings.TrimSuffix(d.lastReleasedApiXmlFile.Base(), d.lastReleasedApiXmlFile.Ext())).
+				FlagWithArg("-oldapidir ", filepath.Dir(d.lastReleasedApiXmlFile.String())).
+				Implicit(d.lastReleasedApiXmlFile)
+		}
 
 		rule.Command().
 			BuiltTool(ctx, "soong_zip").
diff --git a/java/sdk_library.go b/java/sdk_library.go
index 7ce0912..26bd670 100644
--- a/java/sdk_library.go
+++ b/java/sdk_library.go
@@ -2188,8 +2188,12 @@
 			properties.Jars = jars
 			properties.SdkVersion = sdk.sdkVersionForStubsLibrary(ctx.SdkModuleContext(), apiScope)
 			properties.StubsSrcJar = paths.stubsSrcJar.Path()
-			properties.CurrentApiFile = paths.currentApiFilePath.Path()
-			properties.RemovedApiFile = paths.removedApiFilePath.Path()
+			if paths.currentApiFilePath.Valid() {
+				properties.CurrentApiFile = paths.currentApiFilePath.Path()
+			}
+			if paths.removedApiFilePath.Valid() {
+				properties.RemovedApiFile = paths.removedApiFilePath.Path()
+			}
 			s.Scopes[apiScope] = properties
 		}
 	}