JMHing difference between chained and unchained calls

MyBenchmark.java

package org.sample;

/**
 * Results:
 * Benchmark                Mode  Cnt  Score    Error  Units
 * MyBenchmark.testChain    avgt  200  0.019 ±  0.001  us/op
 * MyBenchmark.testNoChain  avgt  200  0.019 ±  0.001  us/op
 */

import org.openjdk.jmh.annotations.Benchmark;
import org.openjdk.jmh.annotations.BenchmarkMode;
import org.openjdk.jmh.annotations.Mode;
import org.openjdk.jmh.annotations.OutputTimeUnit;

import java.util.concurrent.TimeUnit;

public class MyBenchmark {

    @Benchmark
    @BenchmarkMode(Mode.AverageTime)
    @OutputTimeUnit(TimeUnit.MICROSECONDS)
    public String testChain() {
        String foo = " ";
        StringBuffer buf = new StringBuffer();
        buf.append("Hello");
        buf.append(foo);
        buf.append("World");
        return buf.toString();
    }

    @Benchmark
    @BenchmarkMode(Mode.AverageTime)
    @OutputTimeUnit(TimeUnit.MICROSECONDS)
    public String testNoChain() {
        String foo = " ";
        StringBuffer buf = new StringBuffer();
        buf.append("Hello").append(foo).append("World");
        return buf.toString();
    }
}