ComparableComparator.getInstance() not compilable with jdk-compiler

Comparator<Integer> c = ComparableComparator.getInstance();

This line is valid with eclipse (3.4) compiler, but the jdk 1.5.0 compiler returns this error:
[javac] J:\workspace\ndt\cobolclipse-TRUNK\collections_jdk5_branch\src\java\org\apache\commons\collections\comparators\ComparableComparatorTest.java:23: incompatible types; no instance(s) of type variable(s) E exist so that org.apache.commons.collections.comparators.ComparableComparator<E> conforms to java.util.Comparator<java.lang.Integer>
[javac] found : <E>org.apache.commons.collections.comparators.ComparableComparator<E>
[javac] required: java.util.Comparator<java.lang.Integer>
[javac] Comparator<Integer> c = ComparableComparator.getInstance();
[javac] ^
[javac] 1 error