JMeter Groovy: print to log in class (static) (Apparent variable 'log' was found in a static scope but doesn't refer to a local...) - groovy

Question

I want to write to log inside static class in Groovy in JMeter. I can print to terminal inside and outside of class with println or System.out.println. How to do the trick with log? In code below all works except log.warn inside class, give error:
Script53.groovy: 13: Apparent variable 'log' was found in a static scope but doesn't refer to a local variable, static field or class. Possible causes:
You attempted to reference a variable in the binding or an instance variable from a static context.
You misspelled a classname or statically imported field. Please check the spelling.
You attempted to use a method 'log' but left out brackets in a place not allowed by the grammar.
Code:
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
class CalcMain {
static void main(def args) throws Exception {
ScriptEngineManager factory = new ScriptEngineManager();
ScriptEngine engine = factory.getEngineByName("groovy");
println ("testing 1");
System.out.println ("testing 2");
log.warn("warn2");
}
}
OUT.println("testing 4");
println("testing 5");
log.warn("warn 1");
CalcMain test1 = new CalcMain();
test1.main();
I tried web search but could not find an answer.

Answer 1

You can use Groovy #Log4j annotation:
import groovy.util.logging.Log4j
#Log4j
class CalcMain {
static void main(def args) throws Exception {
// some code
log.info "hello there"
}
}

Answer 2

Another option is to send log as parameter to static method:
static void main(org.slf4j.Logger log) throws Exception {
Call method:
test1.main(log);

Answer 3

I've read https://www.blazemeter.com/blog/top-8-jmeter-java-classes-you-should-be-using-with-groovy/ where it is advised to use log variable but also gives link to Logger class. I've tried to play with Logger class and it works:
import javax.script.ScriptEngine;
import javax.script.ScriptEngineManager;
import org.slf4j.Logger;
import org.slf4j.LoggerFactory;
class CalcMain {
static void main(def args) throws Exception {
ScriptEngineManager factory = new ScriptEngineManager();
ScriptEngine engine = factory.getEngineByName("groovy");
final Logger logger = LoggerFactory.getLogger(CalcMain.class);
logger.warn("My warning");
}
}
CalcMain test1 = new CalcMain();
test1.main();