code: protected Violation createViolation(SourceCode sourceCode, ASTNode node, String message) {
          String sourceLine = sourceCode.line(node.getLineNumber()-1);
          return createViolation(node.getLineNumber(), sourceLine, message);
      }
docs: Create a new Violation for the AST node.
  @param sourceCode - the SourceCode
  @param node - the Groovy AST Node
  @param message - the message for the violation; defaults to null