I'm converting my project to 4.0 M2. I'm having this problem and I wonder if it looks familiar to anyone...
 
Exception in thread "main" java.lang.NoSuchFieldError: type
 at org.drools.lang.DRLLexer.mPACKAGE(DRLLexer.java:1186)
 at org.drools.lang.DRLLexer.mTokens(DRLLexer.java:2456)
 at org.antlr.runtime.Lexer.nextToken(Lexer.java:86)
 at org.antlr.runtime.CommonTokenStream.fillBuffer(CommonTokenStream.java:94)
 at org.antlr.runtime.CommonTokenStream.LT(CommonTokenStream.java:237)
 at org.antlr.runtime.CommonTokenStream.LA(CommonTokenStream.java:299)
 at org.drools.lang.DRLParser.prolog(DRLParser.java:362)
 at org.drools.lang.DRLParser.compilation_unit(DRLParser.java:293)
 at org.drools.compiler.DrlParser.compile(DrlParser.java:137)
 at org.drools.compiler.DrlParser.parse(DrlParser.java:56)
 at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:155)
 at test.hxr.TestCompileDrl.testCompileAndExecute(TestCompileDrl.java:76)
 
I know it's probably a library or resource version mismatch but I can't seem chase it down...