UpdateManifest.java contains a check that the value of Main-Class is correctly set in MANIFEST.MF. The test assumes that MANIFEST.MF contains a particular sequence of lines, in particular, that the third line will contain Main-Class:. But if any of the prior lines in MANIFEST.MF exceed the line length limit, they will have been continued on subsequent lines, and Main-Class can be on some line past the third, and the test can, incorrectly, fail.