Neg09.java:17:12: compiler.warn.override.unchecked.ret: (compiler.misc.unchecked.implement: m(), Neg09.C1, m(), Neg09.I), java.util.List, java.util.List Neg09.java:20:21: compiler.warn.override.unchecked.ret: (compiler.misc.unchecked.implement: m(), Neg09.C3, m(), Neg09.I), java.util.List, java.util.List - compiler.err.warnings.and.werror 1 error 2 warnings