The same way as with regular header parameters, when you have underscore characters in the parameter names, they are **automatically converted to hyphens**.

For example, if you have a header parameter `save_data` in the code, the expected HTTP header will be `save-data`, and it will show up like that in the docs.

If for some reason you need to disable this automatic conversion, you can do it as well for Pydantic models for header parameters.

    @BeforeClass
    public static void beforeClass() throws Exception {
        runner = new OpenSearchRunner();
        runner.onBuild((number, settingsBuilder) -> {
            settingsBuilder.put("http.cors.enabled", true);
            settingsBuilder.put("discovery.type", "single-node");
            // settingsBuilder.putList("discovery.seed_hosts", "127.0.0.1:9301");

    assertRoute(selection2.next(), address, proxyB, dns.lookup(PROXY_B_HOST, 0), PROXY_B_PORT)
    dns.assertRequests(PROXY_B_HOST)
    assertThat(selection2.hasNext()).isFalse()

    // No more proxies to try.
    assertThat(routeSelector.hasNext()).isFalse()
  }

  @Test fun proxySelectorDirectConnectionsAreSkipped() {
    val address = factory.newAddress()
    proxySelector.proxies.add(Proxy.NO_PROXY)

import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible
@NullMarked
final class ReflectionFreeAssertThrows {
  interface ThrowingRunnable {
    void run() throws Throwable;
  }

  interface ThrowingSupplier {

import com.google.common.collect.testing.features.MapFeature;
import java.util.Iterator;
import java.util.Map.Entry;
import org.junit.Ignore;

/**
 * Tester for {@code Multimap.entries}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible
@Ignore("test runners must not instantiate and run this directly, only via suites we build")

import com.google.common.collect.testing.features.MapFeature;
import java.util.concurrent.ConcurrentMap;
import org.jspecify.annotations.NullMarked;
import org.junit.Ignore;

/**
 * A generic JUnit test which tests {@code replace(K, V, V)} operations on a concurrent map. Can't
 * be invoked directly; please see {@link
 * com.google.common.collect.testing.ConcurrentMapTestSuiteBuilder}.
 *
 * @author Louis Wasserman
 */
@GwtCompatible

import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible
@NullMarked
final class ReflectionFreeAssertThrows {
  interface ThrowingRunnable {
    void run() throws Throwable;
  }

  interface ThrowingSupplier {

import junit.framework.Test;
import junit.framework.TestCase;
import junit.framework.TestSuite;
import org.jspecify.annotations.NullUnmarked;
import org.jspecify.annotations.Nullable;

/**
 * Tests for {@code ForwardingList}.
 *
 * @author Robert Konigsberg
 * @author Louis Wasserman
 */
@NullUnmarked
public class ForwardingListTest extends TestCase {

import static com.google.common.collect.Hashing.smear;

import com.google.common.annotations.GwtCompatible;
import junit.framework.TestCase;
import org.jspecify.annotations.NullMarked;

/** Tests for {@code Hashing}. */
@GwtCompatible
@NullMarked
public class HashingTest extends TestCase {
  public void testSmear() {
    assertEquals(1459320713, smear(754102528));
    assertEquals(-160560296, smear(1234567890));

import java.util.concurrent.TimeoutException;
import junit.framework.AssertionFailedError;
import org.jspecify.annotations.NullMarked;
import org.jspecify.annotations.Nullable;

/** Replacements for JUnit's {@code assertThrows} that work under GWT/J2CL. */
@GwtCompatible
@NullMarked
final class ReflectionFreeAssertThrows {
  interface ThrowingRunnable {
    void run() throws Throwable;
  }

  interface ThrowingSupplier {