Apache Iceberg version

None

Please describe the bug 🐞

Context: #2409 (comment)

Class with mutable state as class attributes is shared across threads, this creates thread-safety issues. An example of this can be seen in #2409

Let's check and fix this pattern in the codebase. I generated a script to check this.

Would be great to add some kind of test to prevent this in the future

Willingness to contribute

• I can contribute a fix for this bug independently
• I would be willing to contribute a fix for this bug with guidance from the Iceberg community
• I cannot contribute a fix for this bug at this time