Never convert null into an empty request body.

This is a behavior change.

okcurl/src/test/java/com/squareup/okhttp/curl/MainTest.java

@@ -34,10 +34,10 @@ public class MainTest {
   }
 
   @Test public void put() throws IOException {
-    Request request = fromArgs("-X", "PUT", "http://example.com").createRequest();
+    Request request = fromArgs("-X", "PUT", "-d", "foo", "http://example.com").createRequest();
     assertEquals("PUT", request.method());
     assertEquals("http://example.com", request.urlString());
-    assertEquals(0, request.body().contentLength());
+    assertEquals(3, request.body().contentLength());
   }
 
   @Test public void dataPost() {

okhttp-android-support/src/main/java/com/squareup/okhttp/internal/huc/JavaApiConverter.java

@@ -19,10 +19,12 @@ import com.squareup.okhttp.Handshake;
 import com.squareup.okhttp.Headers;
 import com.squareup.okhttp.MediaType;
 import com.squareup.okhttp.Request;
+import com.squareup.okhttp.RequestBody;
 import com.squareup.okhttp.Response;
 import com.squareup.okhttp.ResponseBody;
 import com.squareup.okhttp.internal.Util;
 import com.squareup.okhttp.internal.http.CacheRequest;
+import com.squareup.okhttp.internal.http.HttpMethod;
 import com.squareup.okhttp.internal.http.OkHeaders;
 import com.squareup.okhttp.internal.http.StatusLine;
 import java.io.IOException;
@@ -51,6 +53,7 @@ import okio.Sink;
  * Helper methods that convert between Java and OkHttp representations.
  */
 public final class JavaApiConverter {
+  private static final RequestBody EMPTY_REQUEST_BODY = RequestBody.create(null, new byte[0]);
 
   private JavaApiConverter() {
   }
@@ -163,10 +166,14 @@ public final class JavaApiConverter {
    */
   public static Request createOkRequest(
       URI uri, String requestMethod, Map<String, List<String>> requestHeaders) {
+    // OkHttp's Call API requires a placeholder body; the real body will be streamed separately.
+    RequestBody placeholderBody = HttpMethod.requiresRequestBody(requestMethod)
+        ? EMPTY_REQUEST_BODY
+        : null;
 
     Request.Builder builder = new Request.Builder()
         .url(uri.toString())
-        .method(requestMethod, null);
+        .method(requestMethod, placeholderBody);
 
     if (requestHeaders != null) {
       Headers headers = extractOkHeaders(requestHeaders);

okhttp-tests/src/test/java/com/squareup/okhttp/CallTest.java

@@ -259,7 +259,7 @@ public final class CallTest {
 
     Request request = new Request.Builder()
         .url(server.getUrl("/"))
-        .method("POST", null)
+        .method("POST", RequestBody.create(null, new byte[0]))
         .build();
 
     executeSynchronously(request)

okhttp-urlconnection/src/main/java/com/squareup/okhttp/internal/huc/HttpURLConnectionImpl.java

@@ -23,6 +23,7 @@ import com.squareup.okhttp.Headers;
 import com.squareup.okhttp.OkHttpClient;
 import com.squareup.okhttp.Protocol;
 import com.squareup.okhttp.Request;
+import com.squareup.okhttp.RequestBody;
 import com.squareup.okhttp.Response;
 import com.squareup.okhttp.Route;
 import com.squareup.okhttp.internal.Internal;
@@ -73,6 +74,7 @@ import okio.Sink;
 public class HttpURLConnectionImpl extends HttpURLConnection {
   private static final Set<String> METHODS = new LinkedHashSet<>(
       Arrays.asList("OPTIONS", "GET", "HEAD", "POST", "PUT", "DELETE", "TRACE", "PATCH"));
+  private static final RequestBody EMPTY_REQUEST_BODY = RequestBody.create(null, new byte[0]);
 
   final OkHttpClient client;
 
@@ -314,9 +316,13 @@ public class HttpURLConnectionImpl extends HttpURLConnection {
 
   private HttpEngine newHttpEngine(String method, Connection connection,
       RetryableSink requestBody, Response priorResponse) {
+    // OkHttp's Call API requires a placeholder body; the real body will be streamed separately.
+    RequestBody placeholderBody = HttpMethod.requiresRequestBody(method)
+        ? EMPTY_REQUEST_BODY
+        : null;
     Request.Builder builder = new Request.Builder()
         .url(getURL())
-        .method(method, null /* No body; that's passed separately. */);
+        .method(method, placeholderBody);
     Headers headers = requestHeaders.build();
     for (int i = 0, size = headers.size(); i < size; i++) {
       builder.addHeader(headers.name(i), headers.value(i));

okhttp/src/main/java/com/squareup/okhttp/Request.java

@@ -16,7 +16,6 @@
 package com.squareup.okhttp;
 
 import com.squareup.okhttp.internal.Platform;
-import com.squareup.okhttp.internal.Util;
 import com.squareup.okhttp.internal.http.HttpMethod;
 import java.io.IOException;
 import java.net.MalformedURLException;
@@ -215,7 +214,7 @@ public final class Request {
     }
 
     public Builder delete() {
-      return method("DELETE", null);
+      return delete(RequestBody.create(null, new byte[0]));
     }
 
     public Builder put(RequestBody body) {
@@ -233,8 +232,8 @@ public final class Request {
       if (body != null && !HttpMethod.permitsRequestBody(method)) {
         throw new IllegalArgumentException("method " + method + " must not have a request body.");
       }
-      if (body == null && HttpMethod.permitsRequestBody(method)) {
+      if (body == null && HttpMethod.requiresRequestBody(method)) {
-        body = RequestBody.create(null, Util.EMPTY_BYTE_ARRAY);
+        throw new IllegalArgumentException("method " + method + " must have a request body.");
       }
       this.method = method;
       this.body = body;