void testJoinWithMixedCharSequenceTypes() {
        String str = "string";
        StringBuilder builder = new StringBuilder("builder");
        StringBuffer buffer = new StringBuffer("buffer");
        String result = StringUtil.join(",", str, builder, buffer);
        assertEquals("string,builder,buffer", result);
    }

    @ParameterizedTest
    @DisplayName("Should handle various element counts")

import org.junit.Ignore;

/**
 * Tests {@link java.util.List#hashCode}.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class ListHashCodeTester<E> extends AbstractListTester<E> {

 * com.google.common.collect.testing.ListTestSuiteBuilder}.
 *
 * @author Chris Povirk
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class ListCreationTester<E> extends AbstractListTester<E> {

import org.junit.Ignore;

/**
 * Tests {@link java.util.Collection#equals}.
 *
 * @author George van den Driessche
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class CollectionEqualsTester<E> extends AbstractCollectionTester<E> {

 * interface will be discovered through the Java ServiceLoader mechanism and their provided
 * packaging types will be available throughout the Maven build process.
 * <p>
 * Example usage:
 * <pre>
 * public class CustomPackagingProvider implements PackagingProvider {
 *     public Collection&lt;Packaging&gt; provides() {
 *         return Arrays.asList(

 * Classes implementing this interface can be discovered and loaded by Maven through the
 * Java ServiceLoader mechanism, allowing plugins and extensions to contribute functionality
 * to the Maven build process.
 * <p>
 * SPI services are typically registered in {@code META-INF/services/} files corresponding to
 * the specific service interface being implemented.
 * <p>

 * please see {@link com.google.common.collect.testing.SetTestSuiteBuilder}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class MultisetReadsTester<E> extends AbstractMultisetTester<E> {

import org.junit.Ignore;

/**
 * Tests for {@link Multimap#clear()}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")

 * there are multiple occurrences of elements.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
@NullMarked

 * please see {@link com.google.common.collect.testing.SetTestSuiteBuilder}.
 *
 * @author Jared Levy
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")
// @Ignore affects the Android test runner, which respects JUnit 4 annotations on JUnit 3 tests.
@SuppressWarnings("JUnit4ClassUsedInJUnit3")
public class MultisetReadsTester<E> extends AbstractMultisetTester<E> {