GWT Highcharts is a freely available open source library that provides an elegant and feature complete approach for including Highcharts and Highstock visualizations within a GWT application using pure Java code.
Detailed documentation, demonstration of the different chart types, and source examples can be found on the project home page.
Note that this GitHub repository is the new home GWT Highcharts going forward, and it therefore effectively replaces the SourceForge project with the same name.