Fix the API build

In 28694a09c9 a conflict in the merge
from stable-2.8 was not resolved properly and the API build was broken.

Add back the missing part to fix the build.

Change-Id: I2b0295212631ffad0ba4b57c77b5935b8200d384

gerrit-plugin-gwtui/BUCK

@@ -20,3 +20,13 @@ java_library(
   resources = glob(['src/main/**/*']),
   visibility = ['PUBLIC'],
 )
+
+java_doc(
+  name = 'gwtui-api-javadoc',
+  title = 'Gerrit Review GWT Extension API Documentation',
+  pkg = 'com.google.gerrit.plugin',
+  paths = ['$SRCDIR/src/main/java'],
+  srcs = SRCS,
+  deps = DEPS,
+  visibility = ['PUBLIC'],
+)