Easy Forms uses deprecated HST methods that have been removed in 7.9

Compilation of the 7.9 branch of Easy Forms [1] fails with the message:

[ERROR] Failed to execute goal org.apache.maven.plugins:maven-compiler-plugin:2.5.1:compile (default-compile) on project easy-forms-hst: Compilation failure
[ERROR] /home/mathijs/projects/forge/easyforms/wicket-6-upgrade/hst/src/main/java/org/onehippo/forge/easyforms/hst/BaseEasyFormComponent.java:[94,4] error: method does not override or implement a method from a supertype

[1] https://forge.onehippo.org/svn/easy-forms/easy-forms/branches/wicket-6-upgrade