public void appendHeaders(Request.Builder builder, Map<String, String> headers) {
if (builder == null) {
throw new IllegalArgumentException("builder can not be empty!");
}
Headers.Builder headerBuilder = new Headers.Builder();
<BUG>if (headers == null || headers.isEmpty()) return;
</BUG>
for (String key : headers.keySet()) {
headerBuilder.add(key, headers.get(key));
}

public void appendHeaders(Request.Builder builder, Map<String, String> headers) {
if (builder == null) {
throw new IllegalArgumentException("builder can not be empty!");
}
Headers.Builder headerBuilder = new Headers.Builder();
if (headers == null || headers.isEmpty()) return ;
for (String key : headers.keySet()) {
headerBuilder.add(key, headers.get(key));
}
