JDK 8 compatibility broken with wide character support

[lread]

Version
Current master (as of this writing 17f2f23)

Platform
All JDK v8

Symptom
Throws java.lang.ClassCastException when attempting to fill input.

Reproduction

(require '[etaoin.api :as e])

(def driver (e/firefox))

(e/go driver "https://google.com")

(e/fill driver :active "hello")

Actual behavior
throws exception when calling fill:

user> *e
;; => #error {
 :cause "java.lang.Integer cannot be cast to java.lang.Character"
 :via
 [{:type java.lang.ClassCastException
   :message "java.lang.Integer cannot be cast to java.lang.Character"
   :at [etaoin.api$codepoints$fn__16937 invoke "api.clj" 2821]}]
 :trace
 [[etaoin.api$codepoints$fn__16937 invoke "api.clj" 2821]
  [clojure.core$map$fn__5587 invoke "core.clj" 2745]
  [clojure.lang.LazySeq sval "LazySeq.java" 40]
  [clojure.lang.LazySeq seq "LazySeq.java" 49]
  [clojure.lang.RT seq "RT.java" 528]
  [clojure.core$seq__5124 invokeStatic "core.clj" 137]
  [clojure.core$apply invokeStatic "core.clj" 652]
  [clojure.string$join invokeStatic "string.clj" 180]
  [clojure.string$join invoke "string.clj" 180]
  [etaoin.api$eval16954$fn__16955 doInvoke "api.clj" 2858]
  [clojure.lang.RestFn invoke "RestFn.java" 445]
  [clojure.lang.MultiFn invoke "MultiFn.java" 238]
  [clojure.lang.AFn applyToHelper "AFn.java" 160]
  [clojure.lang.AFn applyTo "AFn.java" 144]
  [clojure.core$apply invokeStatic "core.clj" 663]
  [clojure.core$apply invoke "core.clj" 652]
  [etaoin.api$fill invokeStatic "api.clj" 2894]
  [etaoin.api$fill doInvoke "api.clj" 2883]
  [clojure.lang.RestFn invoke "RestFn.java" 445]
  [user$eval17744 invokeStatic "NO_SOURCE_FILE" 7]
  [user$eval17744 invoke "NO_SOURCE_FILE" 7]
  [clojure.lang.Compiler eval "Compiler.java" 7062]
  [clojure.lang.Compiler eval "Compiler.java" 7025]
  [clojure.core$eval invokeStatic "core.clj" 3206]
  [clojure.core$eval invoke "core.clj" 3202]
  [nrepl.middleware.interruptible_eval$evaluate$fn__1363$fn__1364 invoke "interruptible_eval.clj" 87]
  [clojure.lang.AFn applyToHelper "AFn.java" 152]
  [clojure.lang.AFn applyTo "AFn.java" 144]
  [clojure.core$apply invokeStatic "core.clj" 657]
  [clojure.core$with_bindings_STAR_ invokeStatic "core.clj" 1965]
  [clojure.core$with_bindings_STAR_ doInvoke "core.clj" 1965]
  [clojure.lang.RestFn invoke "RestFn.java" 425]
  [nrepl.middleware.interruptible_eval$evaluate$fn__1363 invoke "interruptible_eval.clj" 87]
  [clojure.main$repl$read_eval_print__8572$fn__8575 invoke "main.clj" 243]
  [clojure.main$repl$read_eval_print__8572 invoke "main.clj" 243]
  [clojure.main$repl$fn__8581 invoke "main.clj" 261]
  [clojure.main$repl invokeStatic "main.clj" 261]
  [clojure.main$repl doInvoke "main.clj" 177]
  [clojure.lang.RestFn invoke "RestFn.java" 1523]
  [nrepl.middleware.interruptible_eval$evaluate invokeStatic "interruptible_eval.clj" 84]
  [nrepl.middleware.interruptible_eval$evaluate invoke "interruptible_eval.clj" 56]
  [nrepl.middleware.interruptible_eval$interruptible_eval$fn__1396$fn__1400 invoke "interruptible_eval.clj" 152]
  [clojure.lang.AFn run "AFn.java" 22]
  [nrepl.middleware.session$session_exec$main_loop__1465$fn__1469 invoke "session.clj" 218]
  [nrepl.middleware.session$session_exec$main_loop__1465 invoke "session.clj" 217]
  [clojure.lang.AFn run "AFn.java" 22]
  [java.lang.Thread run "Thread.java" 750]]}

Expected behavior
Fills the field

Diagnosis
In #552, we used (Character/toString int codepoint), a signature introduced in jdk11.

Action
I'll follow up:

• Find a jdk8-compatible technique to achieve the same effect.
• CI testing should exercise jdk8 (but we don't need to exercise each supported jdk under all browser/OS combos, that would be too many flakey CI jobs)

Failing that, will bump min jdk to 11.