Different compilation behavior using a built-from-source jar vs maven central jar

[brownp2k]

Describe your Issue

We have a requirement to use our own built-from-source jars. When building jackson-databind 2.18.0 from source and using the resulting jar in our project, our own project compilation fails because jackson-databind enables Java 11 preview features. However, our own project compilation succeeds when using the jackson-databind 2.18.0 jar from maven central.

The error we see using the built-from-source jar:
error: classfile for C:\Users\<user>\.gradle\caches\modules-2\files-2.1\com.fasterxml.jackson.core\jackson-databind\2.18.0\3ddbe54c9c69b46e8f56fd63d968d6b311ce5be6\jackson-databind-2.18.0.jar(/com/fasterxml/jackson/databind/node/ArrayNode.class) uses preview features of Java SE 11.

I have so far been unable to determine the difference with the jar we build is vs what was officially published, but there is definitely a difference in behavior. Does anyone have insight into what would cause this behavioral difference?

[brownp2k]

Ah, the maven central jar was built with Java 8. I was building jackson-databind with Java 11 and switching to build with Java 8 resolved the issue I was seeing.

In version 2.15.2 the --enable-preview flag was only applied to Java 14. Starting in 2.16.0 the flag is now applied to Java 11.

[yawkat]

wild to think that my code is used to simulate laser weapons 😄

[cowtowncoder]

Hmmh. So preview feature enabling must be from pom.xml?
Anyway glad you got it working: yes, we try to make sure to build jars with JDK 8 since that is the baseline (well for annotations Java 6 in theory), for Jackson 2.x.

[brownp2k]

Hmmh. So preview feature enabling must be from pom.xml?

Yep, this line:

jackson-databind/pom.xml

Line 333 in 896c1cf

<arg>--enable-preview</arg>

Anyway glad you got it working: yes, we try to make sure to build jars with JDK 8 since that is the baseline (well for annotations Java 6 in theory), for Jackson 2.x.

Well, as a reference point, we were building 2.15.2 with Java 11, and running our application with Java 11 and everything worked just fine. The pom.xml for 2.15.2 was specifying Java 14 for "--enable-preview", which changed to Java 11 for 2.16.0.

Building with 8 is fine with me and it works well, but I was just caught off guard when it quit working on me. After inspecting the maven central jar manifest I realized the difference was Java 8 vs 11.

[cowtowncoder]

Oh. I don't think we should have --enable-preview at all really. Will see if I can remove it.

[pjfanning]

@cowtowncoder there is 1 test that relies on it - I ran this a few days ago so I don't have its name

It might be useful to move that test to a separate module

[cowtowncoder]

@pjfanning I am not sure I see that, see #4760 which seems to pass. Same running locally.

[cowtowncoder]

Removed --enable-preview from JDK 11 profile; things seem to work still. Thank you @brownp2k for reporting this.