IssueTracker

With AGP up until 4.1.0-alpha09 you could have this in your defaultConfig block:

buildConfigField "String", "CONFERENCE_TIMEZONE", "PST"
buildConfigField "java.util.OptionalInt", "FOO_BAR", "java.util.OptionalInt.empty()"
buildConfigField "float", "MAP_CAMERA_FOCUS_ZOOM", "5f"

This builds correctly, and in BuildConfig you'll see these fields:

public final class BuildConfig {
  public static final String CONFERENCE_TIMEZONE = "PST";
  public static final java.util.OptionalInt FOO_BAR = java.util.OptionalInt.empty();
  public static final float MAP_CAMERA_FOCUS_ZOOM = 5f;
  ...

However, in 4.1.0-dev this no longer works; the build aborts with Unsupported BuildConfig type : float or Unsupported BuildConfig type : java.util.OptionalInt depending on the order.

(These things were actively used; for example, this is why iosched no longer builds/syncs with 4.1.0-dev; see line 41 for a float and 37 for fully-qualified-name class usages of this here: https://github.com/google/iosched/blob/master/mobile/build.gradle#L37 )