Spatial4j 0.4 should be released the week of January 13th; a snapshot is published. A longer version of the delta from 0.4 is in CHANGES.md
A couple notable new features are:
- Built-in WKT parser without relying on JTS. The older shape string format is deprecated.
- A binary shape codec for reading & writing the shapes to a byte-stream in a reasonably compact manner.