Warn on incorrect Jackson version at runtime?

[ivarref]

Hi,

and thanks for a fine library!

Re the twitter thread https://twitter.com/arcatan/status/1159690520194670598

Do you know if there’s something that jsonista could do better around this? Mixed-up Jackson deps seems to be a thing that keeps happening.

I'm not sure this is a good suggestion, but one option is, at runtime, to verify Jackson versions. This is stored inside for example META-INF/maven/com.fasterxml.jackson.core/jackson-core/pom.properties.

~/.m2/repository/com/fasterxml/jackson/core/jackson-core/2.9.9$ unzip -p jackson-core-2.9.9.jar META-INF/maven/com.fasterxml.jackson.core/jackson-core/pom.properties
#Generated by org.apache.felix.bundleplugin
#Wed May 15 19:58:39 PDT 2019
version=2.9.9
groupId=com.fasterxml.jackson.core
artifactId=jackson-core

I'm no Java/JAR-expert, but this file is similarly also stored inside my uberjar (packed by boot).

$ unzip -p target/app.jar META-INF/maven/com.fasterxml.jackson.core/jackson-core/pom.properties
#Generated by org.apache.felix.bundleplugin
#Mon Jun 11 17:53:30 PDT 2018
version=2.9.6
groupId=com.fasterxml.jackson.core
artifactId=jackson-core

Thus the version can be read in Clojure, at runtime, with something like this:

(defn dump-version [pom-props]
  (some->> (io/resource pom-props)
           (slurp)
           (str/split-lines)
           (filter #(str/starts-with? % "version="))
           (first)
           (seq)
           (drop (count "version="))
           (str/join "")))

$ (dump-version "META-INF/maven/com.fasterxml.jackson.core/jackson-core/pom.properties")
=> "2.9.9"

When an incorrect version is detected, an error/warning could be printed.

I have not myself written code like this that is running in production, but if it saves hours of devs debugging time with strange behaviour due to a slightly incorrect dependency, it might be worth it?
Consider this a suggestion.

CC @miikka @hlship

Thanks and kind regards.