Different results from using Java 11 and 17

[tomasbjerre]

I am getting different results when using Java 11 and 17. I am not sure if it is an issue with this library, or a "feature" in Java 17...

Here is the code, also available here:
https://github.com/tomasbjerre/handlebars-issue

dependencies {
 api 'com.github.jknack:handlebars:4.3.0'

 testImplementation 'junit:junit:4.12'
 testImplementation 'org.slf4j:slf4j-simple:1.7.13'
 testImplementation 'org.assertj:assertj-core:2.3.0'
}

The assertions at the end of the test case shows how it differs.

import java.io.StringWriter;
import java.io.Writer;

import org.junit.Test;

import com.github.jknack.handlebars.Context;
import com.github.jknack.handlebars.Handlebars;
import com.github.jknack.handlebars.Template;

public class TemplatesTest {

  public class Issue {
    private final boolean theVal;

    public Issue() {
      this.theVal = true;
    }

    public boolean isTheVal() {
      return this.theVal;
    }
  }

  @Test
  public void test() throws Exception {
    final Handlebars handlebars = new Handlebars();
    final Template template =
        handlebars.compileInline("{{isTheVal}}\n" + "isTheVal: {{#isTheVal}}yes{{/isTheVal}}\n");
    final Object context = new Issue();

    final Context changelogContext = Context.newContext(context);
    final Writer writer = new StringWriter();
    template.apply(changelogContext, writer);
    final String rendered = writer.toString();

    // Java 17
    // assertThat(rendered).isEqualTo("true\n" + "isTheVal: yes\n");
    // Java 11
    assertThat(rendered).isEqualTo("\n" + "isTheVal: \n");
  }
}

Java versions tested

$ javac -version
javac 17.0.1

$ java -version
openjdk version "17.0.1" 2021-10-19
OpenJDK Runtime Environment (build 17.0.1+12-Ubuntu-120.04)
OpenJDK 64-Bit Server VM (build 17.0.1+12-Ubuntu-120.04, mixed mode, sharing)

$ javac -version
javac 11.0.13

$ java -version
openjdk version "11.0.13" 2021-10-19
OpenJDK Runtime Environment (build 11.0.13+8-Ubuntu-0ubuntu1.20.04)
OpenJDK 64-Bit Server VM (build 11.0.13+8-Ubuntu-0ubuntu1.20.04, mixed mode, sharing)

[agentgt]

The default value resolvers are different when using different JDKs. See https://github.com/jknack/handlebars.java/blob/master/handlebars/src/main/java/com/github/jknack/handlebars/ValueResolver.java#L87

@jknack This changed seemed to cause lots of confusion. Maybe some doc needs to be added.