apache-httpclient library generates code that does not compile

Using the attached precisely openapi schema the apache-httpclient library generates this code that does not compile.

if (getCosts() != null) { joiner.add(getCosts().toUrlQueryString(prefix + "costs" + suffix)); }

The above happens in the RouteResponse & TravelBoundary classes. It is failing because getCosts() returns an array, the code does not handle arrays only single objects.
PreciselyAPIs_OpenAPI.zip

Using the attached fanniemae openapi schema the apache-httpclient library generates this code that does not compile.

for (String _item : getAllow()) { try { joiner.add(String.format("%sallow%s%s=%s", prefix, suffix, "".equals(suffix) ? "" : String.format("%s%d%s", containerPrefix, i, containerSuffix), URLEncoder.encode(String.valueOf(_item), "UTF-8").replaceAll("\\+", "%20"))); } catch (UnsupportedEncodingException e) { // Should never happen, UTF-8 is always supported throw new RuntimeException(e); } }

The above happens in both the HttpHeaders & the ResponseEntityHeaders class.
Income_Limits_API.json

Start by generating the apache-httpclient client with the attached PreciselyAPIs_OpenAPI.zip and Income_Limits_API.json schemas, then inspect the generated RouteResponse, TravelBoundary, HttpHeaders, and ResponseEntityHeaders classes. Trace the generated query-string code for array-valued fields and verify the generated client compiles for both schemas. Done means the reported array cases no longer produce uncompilable Java code.