Add dependency on diffutils

com_google_truth has a dependency on diffutils that we're not exposing.  This
becomes problematic in cases where certain tests fail and the equality check
can't show the difference.  If this happens, instead of the original failure
all we see is a failure to load diffutils.

Note that com_google_truth appears to have some other dependencies that we are
also not exposing, but that so far these have not been problematic.

-------------
Created by MOE: https://github.com/google/moe
MOE_MIGRATED_REVID=214774587

java/google/registry/repositories.bzl

@@ -72,6 +72,7 @@ def domain_registry_repositories(
         omit_com_google_googlejavaformat_google_java_format = False,
         omit_com_google_guava = False,
         omit_com_google_guava_testlib = False,
+        omit_com_google_gwt_user = False,
         omit_com_google_http_client = False,
         omit_com_google_http_client_appengine = False,
         omit_com_google_http_client_jackson2 = False,
@@ -88,6 +89,7 @@ def domain_registry_repositories(
         omit_com_google_template_soy = False,
         omit_com_google_truth = False,
         omit_com_google_truth_extensions_truth_java8_extension = False,
+        omit_com_googlecode_java_diff_utils_diffutils = False,
         omit_com_googlecode_charts4j = False,
         omit_com_googlecode_json_simple = False,
         omit_com_ibm_icu_icu4j = False,
@@ -117,6 +119,7 @@ def domain_registry_repositories(
         omit_javax_inject = False,
         omit_javax_mail = False,
         omit_javax_servlet_api = False,
+        omit_javax_validation_api = False,
         omit_javax_xml_bind_jaxb_api = False,
         omit_javax_xml_soap_api = False,
         omit_javax_xml_ws_jaxws_api = False,
@@ -262,6 +265,8 @@ def domain_registry_repositories(
         com_google_guava()
     if not omit_com_google_guava_testlib:
         com_google_guava_testlib()
+    if not omit_com_google_gwt_user:
+        com_google_gwt_user()
     if not omit_com_google_http_client:
         com_google_http_client()
     if not omit_com_google_http_client_appengine:
@@ -294,6 +299,8 @@ def domain_registry_repositories(
         com_google_truth()
     if not omit_com_google_truth_extensions_truth_java8_extension:
         com_google_truth_extensions_truth_java8_extension()
+    if not omit_com_googlecode_java_diff_utils_diffutils:
+        com_googlecode_java_diff_utils_diffutils()
     if not omit_com_googlecode_charts4j:
         com_googlecode_charts4j()
     if not omit_com_googlecode_json_simple:
@@ -352,6 +359,8 @@ def domain_registry_repositories(
         javax_mail()
     if not omit_javax_servlet_api:
         javax_servlet_api()
+    if not omit_javax_validation_api:
+        javax_validation_api()
     if not omit_javax_xml_bind_jaxb_api:
         javax_xml_bind_jaxb_api()
     if not omit_javax_xml_soap_api:
@@ -1342,6 +1351,23 @@ def com_google_guava_testlib():
         ],
     )
 
+def com_google_gwt_user():
+    java_import_external(
+        name = "com_google_gwt_user",
+        neverlink = 1,
+        licenses = ["notice"],  # GWT Terms
+        jar_sha256 = "9f420f0d0c2f177d71cb1794b3be1418f9755f6e4181101af3951b8302b9556d",
+        jar_urls = [
+            "http://maven.ibiblio.org/maven2/com/google/gwt/gwt-user/2.8.2/gwt-user-2.8.2.jar",
+            "http://repo1.maven.org/maven2/com/google/gwt/gwt-user/2.8.2/gwt-user-2.8.2.jar",
+        ],
+        deps = [
+            "@javax_validation_api",
+            "@javax_servlet_api",
+            "@org_w3c_css_sac",
+        ],
+    )
+
 def com_google_http_client():
     java_import_external(
         name = "com_google_http_client",
@@ -1547,6 +1573,7 @@ def com_google_truth():
             "@junit",
             "@com_google_auto_value",
             "@com_google_errorprone_error_prone_annotations",
+            "@com_googlecode_java_diff_utils_diffutils",
         ],
     )
 
@@ -1577,6 +1604,17 @@ def com_googlecode_charts4j():
         licenses = ["notice"],  # The MIT License
     )
 
+def com_googlecode_java_diff_utils_diffutils():
+    java_import_external(
+        name = "com_googlecode_java_diff_utils_diffutils",
+        licenses = ["notice"],  # The Apache Software License, Version 2.0
+        jar_sha256 = "61ba4dc49adca95243beaa0569adc2a23aedb5292ae78aa01186fa782ebdc5c2",
+        jar_urls = [
+            "http://maven.ibiblio.org/maven2/com/googlecode/java-diff-utils/diffutils/1.3.0/diffutils-1.3.0.jar",
+            "http://repo1.maven.org/maven2/com/googlecode/java-diff-utils/diffutils/1.3.0/diffutils-1.3.0.jar",
+        ],
+    )
+
 def com_googlecode_json_simple():
     java_import_external(
         name = "com_googlecode_json_simple",
@@ -1907,6 +1945,17 @@ def javax_servlet_api():
         licenses = ["notice"],  # Apache
     )
 
+def javax_validation_api():
+    java_import_external(
+        name = "javax_validation_api",
+        licenses = ["notice"],  # Apache License, Version 2.0
+        jar_sha256 = "e459f313ebc6db2483f8ceaad39af07086361b474fa92e40f442e8de5d9895dc",
+        jar_urls = [
+            "http://maven.ibiblio.org/maven2/javax/validation/validation-api/1.0.0.GA/validation-api-1.0.0.GA.jar",
+            "http://repo1.maven.org/maven2/javax/validation/validation-api/1.0.0.GA/validation-api-1.0.0.GA.jar",
+        ],
+    )
+
 def javax_xml_bind_jaxb_api():
     java_import_external(
         name = "javax_xml_bind_jaxb_api",