public static Statement rewriteExplicitCondition(AssertStatement stat, IRewriteResources resources,
                                                   String valueRecorderSuffix, String errorCollectorSuffix) {
    ConditionRewriter rewriter = new ConditionRewriter(resources, valueRecorderSuffix, errorCollectorSuffix);
    Expression message = AstUtil.getAssertionMessage(stat);
    return rewriter.rewriteCondition(stat, stat.getBooleanExpression().getExpression(), message, true);
  }
Rewrites explicit ("assert x > 3") and implicit ("x > 3") condition
statements. Replacing the original statement with the rewritten one is up
to clients.

@author Peter Niederwieser
spock-core/src/main/java/org/spockframework/compiler/ConditionRewriter.java