http://openjdk.java.net/projects/code-tools/jmh/jmh-core/: The jmh is a Java harness for building, running, and analysing nano/micro/macro benchmarks written in Java and other languages targeting the JVM. (Oracle)
  • Aleksey Shipilev (Oracle/Sun, Red Hat)
  • Sergey Kuksenko (Oracle/Sun)
  • Anders Astrand (Oracle/BEA)
  • Staffan Friberg (Oracle/BEA)
  • Henrik Loef (Oracle/BEA) 
/*
 * Copyright (c) 2014, 2020, Oracle and/or its affiliates. All rights reserved.
 * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
 *
 * This code is free software; you can redistribute it and/or modify it
 * under the terms of the GNU General Public License version 2 only, as
 * published by the Free Software Foundation.  Oracle designates this
 * particular file as subject to the "Classpath" exception as provided
 * by Oracle in the LICENSE file that accompanied this code.
 *
 * This code is distributed in the hope that it will be useful, but WITHOUT
 * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
 * FITNESS FOR A PARTICULAR PURPOSE.  See the GNU General Public License
 * version 2 for more details (a copy is included in the LICENSE file that
 * accompanied this code).
 *
 * You should have received a copy of the GNU General Public License version
 * 2 along with this work; if not, write to the Free Software Foundation,
 * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
 *
 * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
 * or visit www.oracle.com if you need additional information or have any
 * questions.
 */
package org.openjdk.jmh.results;

import java.util.Collection;

class TextResultAggregator implements Aggregator<TextResult> {
    @Override
    public TextResult aggregate(Collection<TextResult> results) {
        StringBuilder output = new StringBuilder();
        String label = null;
        for (TextResult r : results) {
            output.append(r.output);
            if (label == null) {
                label = r.label;
            } else if (!label.equalsIgnoreCase(r.label)) {
                throw new IllegalStateException("Trying to aggregate different labels: " + label + ", " + r.label);
            }
        }
        return new TextResult(output.toString(), label);
    }
}