Other than gcj, everything compiles with ecj without error (given the attached patch).
The gcj fails on an import which has nothing to do with ecj but with my building the build path.
Gdata as expected needs to be compiled as Java 5. I compiled everything else under both 1.5 and 1.4 compatibility.
I did find that two contrib files are duplicated. These are:
The first pair only differed by whitespace.
The second pair only by a comment and the style of imports.
There is a dependency on queries by xml-query-parser, but non on similarity.
So I'd suggest wacking similarity.