Revert use of java.util.HexFormat (not available in Babashka), and dependency on JDK 17

Author: hlship

CHANGES.md

@@ -2,7 +2,6 @@
 
 *BREAKING CHANGES*
 
-* JDK 17 is now required when using Clojure
 * Groups are now defined in the options passed to `net.lewisship.cli-tools/dispatch`, not in
   namespace metadata
 * Command names are matched as prefixes (not substrings)

README.md

@@ -57,7 +57,6 @@ Documentation starts with [the overview](doc/overview.md).
 ## Compatibility
 
 `cli-tools` is compatible with Clojure 1.11 and above, and w/ Babashka.  
-For Clojure, it requires JDK 17 or above.
 
 ## License
 

src/net/lewisship/cli_tools/cache.cljc

@@ -9,7 +9,6 @@
             [clj-commons.ansi :refer [perr]]
             #?(:bb [babashka.classpath :as cp]))
   (:import (java.io File)
-           (java.util HexFormat)
            (java.nio ByteBuffer)
            (java.security MessageDigest)))
 
@@ -59,10 +58,10 @@
       ;; Adding or removing a file (even if no other files are touched) will change the digest.
       (update-digest-recursively digest f))))
 
-(defn- hex-string 
-  [^bytes input]
-  (-> (HexFormat/of)
-      (.formatHex input)))
+(defn- hex-string [^bytes input]
+  (let [sb (StringBuilder.)]
+    (run! #(.append sb (format "%X" %)) input)
+    (str sb)))
 
 (defn classpath-digest
   "Passed the tool options, return a hex string of the SHA-1 digest of the files from the classpath and