For example:

rule "get directory entries"
when
$d: Directory( $p: pathname, children == null )
then
List kidFiles = browser.getEntries( $p );
modify( $d ){ setChildren( kidFiles ) ; ################################################ missing brace here
end

Exception in thread "main" java.lang.StringIndexOutOfBoundsException: String index out of range: 88
at java.lang.String.substring(String.java:1934)
at org.drools.rule.builder.dialect.DialectUtil.rewriteDescr(DialectUtil.java:581)
at org.drools.rule.builder.dialect.DialectUtil.fixBlockDescr(DialectUtil.java:140)
at org.drools.rule.builder.dialect.DialectUtil.fixBlockDescr(DialectUtil.java:98)
at org.drools.rule.builder.dialect.asm.AbstractASMConsequenceBuilder.consequenceContext(AbstractASMConsequenceBuilder.java:44)
at org.drools.rule.builder.dialect.asm.AbstractASMConsequenceBuilder.build(AbstractASMConsequenceBuilder.java:22)
at org.drools.rule.builder.RuleBuilder.build(RuleBuilder.java:99)
at org.drools.compiler.PackageBuilder.addRule(PackageBuilder.java:2503)
at org.drools.compiler.PackageBuilder.addPackage(PackageBuilder.java:847)
at org.drools.compiler.PackageBuilder.addPackageFromDrl(PackageBuilder.java:443)
at org.drools.compiler.PackageBuilder.addKnowledgeResource(PackageBuilder.java:626)
at org.drools.builder.impl.KnowledgeBuilderImpl.add(KnowledgeBuilderImpl.java:41)