Would the following (avoiding the case insensitive map) not work here?
```
Builder<String, String> services = ImmutableMap.builder()
for (Entry<String, String> entry : from.getHeaders().entries()) {
  String lowerCaseKey = entry.getKey().toLowerCase();
  if (lowerCaseKey.endsWith(URL_SUFFIX.toLowerCase()) { // perhaps add a URL_SUFFIX_LOWER constant?
    services.put(lowerCaseKey, getURI(entry.getValue()).toLowerCase());
  }
...
Obviously, this will differ in that the map will not have case-insensitive _comparison_, simply lowercase-only entries.

@everett-toews: any idea where, if anywhere, the _usage_ of this map would need to be modified to be case-insensitive?