diff --git a/wsclient/src/main/java/com/google/gson/webservice/client/Preconditions.java b/wsclient/src/main/java/com/google/gson/webservice/client/Preconditions.java
new file mode 100644
index 00000000..33422d79
--- /dev/null
+++ b/wsclient/src/main/java/com/google/gson/webservice/client/Preconditions.java
@@ -0,0 +1,31 @@
+/*
+ * Copyright (C) 2010 Google Inc.
+ *
+ * Licensed under the Apache License, Version 2.0 (the "License");
+ * you may not use this file except in compliance with the License.
+ * You may obtain a copy of the License at
+ *
+ * http://www.apache.org/licenses/LICENSE-2.0
+ *
+ * Unless required by applicable law or agreed to in writing, software
+ * distributed under the License is distributed on an "AS IS" BASIS,
+ * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+ * See the License for the specific language governing permissions and
+ * limitations under the License.
+ */
+package com.google.gson.webservice.client;
+
+final class Preconditions {
+
+  public static void checkArgument(boolean condition) {
+    if (!condition) {
+      throw new IllegalArgumentException();
+    }
+  }
+
+  public static void checkNotNull(Object obj) {
+    if (obj == null) {
+      throw new IllegalArgumentException();
+    }
+  }
+}
diff --git a/wsclient/src/main/java/com/google/gson/webservice/client/ResponseReceiver.java b/wsclient/src/main/java/com/google/gson/webservice/client/ResponseReceiver.java
index a7046aa0..7852ac53 100644
--- a/wsclient/src/main/java/com/google/gson/webservice/client/ResponseReceiver.java
+++ b/wsclient/src/main/java/com/google/gson/webservice/client/ResponseReceiver.java
@@ -23,7 +23,6 @@ import java.lang.reflect.Type;
 import java.net.HttpURLConnection;
 import java.util.Map;
 
-import com.google.common.base.Preconditions;
 import com.google.gson.Gson;
 import com.google.gson.webservice.definition.HeaderMap;
 import com.google.gson.webservice.definition.HeaderMapSpec;
@@ -70,13 +69,13 @@ public final class ResponseReceiver {
         paramsBuilder.put(paramName, value, typeOfT);
       }
     }
-    return paramsBuilder.create();
+    return paramsBuilder.build();
   }
 
   private ResponseBody readResponseBody(HttpURLConnection conn, ResponseBodySpec bodySpec) 
       throws IOException {
     if (bodySpec.size() == 0) {
-      return new ResponseBody.Builder(bodySpec).create();
+      return new ResponseBody.Builder(bodySpec).build();
     }
     String connContentType = conn.getContentType();
     Preconditions.checkArgument(connContentType.contains(bodySpec.getContentType()));
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/CallPathMap.java b/wsdef/src/main/java/com/google/gson/webservice/definition/CallPathMap.java
index c083f92a..f12f90c0 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/CallPathMap.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/CallPathMap.java
@@ -39,7 +39,7 @@ public final class CallPathMap<T> {
       return this;
     }
     
-    public CallPathMap<T> create() {
+    public CallPathMap<T> build() {
       return new CallPathMap<T>(contents, nullValue);
     }
   }
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/HeaderMap.java b/wsdef/src/main/java/com/google/gson/webservice/definition/HeaderMap.java
index 4ce3f048..f8294492 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/HeaderMap.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/HeaderMap.java
@@ -41,7 +41,7 @@ public final class HeaderMap extends ParamMap {
       return (Builder) super.put(paramName, content, typeOfContent);
     }
     
-    public HeaderMap create() {
+    public HeaderMap build() {
       return new HeaderMap(spec, contents);
     }
   }
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/HeaderMapSpec.java b/wsdef/src/main/java/com/google/gson/webservice/definition/HeaderMapSpec.java
index 154c9a6d..2ed41f91 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/HeaderMapSpec.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/HeaderMapSpec.java
@@ -34,7 +34,7 @@ public final class HeaderMapSpec implements ParamMapSpec {
       map.put(headerName, headerType);
     }
     
-    public HeaderMapSpec create() {
+    public HeaderMapSpec build() {
       return new HeaderMapSpec(map);
     }
   }
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/RequestBody.java b/wsdef/src/main/java/com/google/gson/webservice/definition/RequestBody.java
index beaf1668..6afa8ead 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/RequestBody.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/RequestBody.java
@@ -44,7 +44,7 @@ public final class RequestBody extends ContentBody {
       return (Builder) super.put(paramName, content, typeOfContent);
     }
     
-    public RequestBody create() {
+    public RequestBody build() {
       return new RequestBody(spec, contents);
     }    
   }
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/RequestBodySpec.java b/wsdef/src/main/java/com/google/gson/webservice/definition/RequestBodySpec.java
index 19c77f1d..8fb1950f 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/RequestBodySpec.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/RequestBodySpec.java
@@ -33,7 +33,7 @@ public final class RequestBodySpec extends ContentBodySpec {
       return this;
     }
     
-    public RequestBodySpec create() {
+    public RequestBodySpec build() {
       RequestBodySpec spec = new RequestBodySpec(paramsSpec);
       return spec;
     }    
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/ResponseBody.java b/wsdef/src/main/java/com/google/gson/webservice/definition/ResponseBody.java
index bd9a0e2d..dcc18b81 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/ResponseBody.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/ResponseBody.java
@@ -41,7 +41,7 @@ public final class ResponseBody extends ContentBody {
       return (Builder) super.put(paramName, content, typeOfContent);
     }
     
-    public ResponseBody create() {
+    public ResponseBody build() {
       return new ResponseBody(spec, contents);
     }    
   }
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/ResponseBodySpec.java b/wsdef/src/main/java/com/google/gson/webservice/definition/ResponseBodySpec.java
index a8863e5f..ceae2601 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/ResponseBodySpec.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/ResponseBodySpec.java
@@ -33,7 +33,7 @@ public final class ResponseBodySpec extends ContentBodySpec {
       return this;
     }
     
-    public ResponseBodySpec create() {
+    public ResponseBodySpec build() {
       ResponseBodySpec spec = new ResponseBodySpec(paramsSpec);
       return spec;
     }    
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/WebServiceCallSpec.java b/wsdef/src/main/java/com/google/gson/webservice/definition/WebServiceCallSpec.java
index f7e29498..3a43f4b4 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/WebServiceCallSpec.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/WebServiceCallSpec.java
@@ -29,7 +29,7 @@ import java.util.Set;
  */
 public final class WebServiceCallSpec {
   
-  public static final WebServiceCallSpec NULL_SPEC = new Builder(new CallPath("")).create();
+  public static final WebServiceCallSpec NULL_SPEC = new Builder(new CallPath("")).build();
   
   public static class Builder {
 	private final CallPath callPath;
@@ -71,14 +71,14 @@ public final class WebServiceCallSpec {
       resBodySpecBuilder.add(paramName, type);
       return this;
     }
-    public WebServiceCallSpec create() {      
+    public WebServiceCallSpec build() {      
       if (supportedHttpMethods.isEmpty()) {
         supportedHttpMethods.addAll(Arrays.asList(HttpMethod.values()));
       }
       RequestSpec requestSpec = 
-        new RequestSpec(reqParamsSpecBuilder.create(), reqBodySpecBuilder.create());
+        new RequestSpec(reqParamsSpecBuilder.build(), reqBodySpecBuilder.build());
       ResponseSpec responseSpec = 
-        new ResponseSpec(resParamsSpecBuilder.create(), resBodySpecBuilder.create());
+        new ResponseSpec(resParamsSpecBuilder.build(), resBodySpecBuilder.build());
       WebServiceCallSpec callSpec = new WebServiceCallSpec(supportedHttpMethods, callPath, 
           requestSpec, responseSpec);
       return callSpec;
diff --git a/wsdef/src/main/java/com/google/gson/webservice/definition/WebServiceResponse.java b/wsdef/src/main/java/com/google/gson/webservice/definition/WebServiceResponse.java
index fde198df..1cb26c0e 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/definition/WebServiceResponse.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/definition/WebServiceResponse.java
@@ -60,8 +60,8 @@ public final class WebServiceResponse {
       return this;
     }
     
-    public WebServiceResponse create() {
-      return new WebServiceResponse(spec, headers.create(), body.create());
+    public WebServiceResponse build() {
+      return new WebServiceResponse(spec, headers.build(), body.build());
     }
   }
   
diff --git a/wsdef/src/main/java/com/google/gson/webservice/typeadapters/RequestBodyGsonConverter.java b/wsdef/src/main/java/com/google/gson/webservice/typeadapters/RequestBodyGsonConverter.java
index 66ec6d29..436d2875 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/typeadapters/RequestBodyGsonConverter.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/typeadapters/RequestBodyGsonConverter.java
@@ -66,11 +66,11 @@ public class RequestBodyGsonConverter implements JsonSerializer<RequestBody>,
       Object value = context.deserialize(entry.getValue(), entryType);
       builder.put(key, value);
     }
-    return builder.create();
+    return builder.build();
   }
 
   @Override
   public RequestBody createInstance(Type type) {
-    return new RequestBody.Builder(spec).create();
+    return new RequestBody.Builder(spec).build();
   }
 }
diff --git a/wsdef/src/main/java/com/google/gson/webservice/typeadapters/ResponseBodyGsonConverter.java b/wsdef/src/main/java/com/google/gson/webservice/typeadapters/ResponseBodyGsonConverter.java
index 1540a675..bf613718 100644
--- a/wsdef/src/main/java/com/google/gson/webservice/typeadapters/ResponseBodyGsonConverter.java
+++ b/wsdef/src/main/java/com/google/gson/webservice/typeadapters/ResponseBodyGsonConverter.java
@@ -66,11 +66,11 @@ public final class ResponseBodyGsonConverter implements JsonSerializer<ResponseB
       Object value = context.deserialize(entry.getValue(), entryType);
       responseBodyBuilder.put(key, value, entryType);
     }
-    return responseBodyBuilder.create();
+    return responseBodyBuilder.build();
   }
 
   @Override
   public ResponseBody createInstance(Type type) {
-    return new ResponseBody.Builder(spec).create();
+    return new ResponseBody.Builder(spec).build();
   }
 }
\ No newline at end of file
diff --git a/wsf/src/main/java/com/google/gson/wsf/server/RequestReceiver.java b/wsf/src/main/java/com/google/gson/wsf/server/RequestReceiver.java
index a3e0324c..9d319834 100644
--- a/wsf/src/main/java/com/google/gson/wsf/server/RequestReceiver.java
+++ b/wsf/src/main/java/com/google/gson/wsf/server/RequestReceiver.java
@@ -81,7 +81,7 @@ public final class RequestReceiver {
         paramsBuilder.put(name, value);
       }
     }
-    return paramsBuilder.create();
+    return paramsBuilder.build();
   }
   
   private RequestBody buildRequestBody(HttpServletRequest request) throws IOException {
@@ -95,6 +95,6 @@ public final class RequestReceiver {
   }
 
   private RequestBody createEmptyRequestBody(RequestBodySpec bodySpec) {
-    return new RequestBody.Builder(bodySpec).create();
+    return new RequestBody.Builder(bodySpec).build();
   }
 }