J2SE-1.5 is enough for this project (and don't store OT-specific options)
diff --git a/contrib/org.eclipse.objectteams.jdt.nullity.tests/.classpath b/contrib/org.eclipse.objectteams.jdt.nullity.tests/.classpath
index aa04ac1..9e7247e 100644
--- a/contrib/org.eclipse.objectteams.jdt.nullity.tests/.classpath
+++ b/contrib/org.eclipse.objectteams.jdt.nullity.tests/.classpath
@@ -1,6 +1,6 @@
<?xml version="1.0" encoding="UTF-8"?>
<classpath>
- <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/JavaSE-1.6"/>
+ <classpathentry kind="con" path="org.eclipse.jdt.launching.JRE_CONTAINER/org.eclipse.jdt.internal.debug.ui.launcher.StandardVMType/J2SE-1.5"/>
<classpathentry kind="con" path="OTRE"/>
<classpathentry kind="src" path="src"/>
<classpathentry kind="src" path="annotations"/>