Update min_sdk_version from SdkSpec to ApiLevel

This relands aosp/2457063. The original change broke T and U since those
branches still contain soong modules of type (kind+level). Those soong
modules have been cleaned up now

Test: Used go/abtd to test T and U branches with this change

Bug: 208456999
Change-Id: I0ef7933c055f88cb512a02108f1173e51156ef1c
diff --git a/java/droiddoc.go b/java/droiddoc.go
index e98b9ea..3e21008 100644
--- a/java/droiddoc.go
+++ b/java/droiddoc.go
@@ -248,8 +248,8 @@
 	return proptools.String(j.properties.System_modules)
 }
 
-func (j *Javadoc) MinSdkVersion(ctx android.EarlyModuleContext) android.SdkSpec {
-	return j.SdkVersion(ctx)
+func (j *Javadoc) MinSdkVersion(ctx android.EarlyModuleContext) android.ApiLevel {
+	return j.SdkVersion(ctx).ApiLevel
 }
 
 func (j *Javadoc) ReplaceMaxSdkVersionPlaceholder(ctx android.EarlyModuleContext) android.SdkSpec {
@@ -304,7 +304,7 @@
 		flags = append(flags, "-I"+src.String())
 	}
 
-	minSdkVersion := j.MinSdkVersion(ctx).ApiLevel.FinalOrFutureInt()
+	minSdkVersion := j.MinSdkVersion(ctx).FinalOrFutureInt()
 	flags = append(flags, fmt.Sprintf("--min_sdk_version=%v", minSdkVersion))
 
 	return strings.Join(flags, " "), deps