Java version is working fine now.

BTW Google kind of think just like you do: https://github.com/google/auto/blob/master/value/userguide/builders.md

Instantiate a builder to instantiate a class every time you want to instantiate a class doesn't seem to be a big gain, please check mor on the topin at this SO answer: https://stackoverflow.com/questions/5007355/builder-pattern-in-effective-java

When you ask for something post a question, not an issue.
See the top of the page: 284 guys passed the Java kata.
It appears that your code is too slow.

Having a problem with this tests...
My IDE runs the code (and the sample tests) within 0.007 sec.
Also the Tests on CodeWars are fine.
But when attampting to pass as solution, i get an java time out exception each time (it took more than 20 sec).

Is this a failing Unit test?

I believe, the Java Testcase has a compilation error

/home/codewarrior/src/main/java/PaginationHelperTest.java:37: error: cannot find symbol
    assertEquals("itemCount is returning incorrect value", 24, helper.itemCount());
                                                                     ^
  symbol:   method itemCount()
  location: variable helper of type PaginationHelper<Integer>
1 error

FAILURE: Build failed with an exception.

* What went wrong:
Execution failed for task ':compileJava'.
> Compilation failed; see the compiler error output for details.

*:

The Build Output:

Dependencies:

junit:junit:4.12
org.projectlombok:lombok:1.16.18
org.mockito:mockito-core:2.7.19
org.assertj:assertj-core:3.8.0
org.xerial:sqlite-jdbc:3.19.3

Tasks:

:compileJava FAILED
1 actionable task: 1 executed


Compiler Warnings:

Note: /home/codewarrior/src/main/java/PaginationHelperTest.java uses unchecked or unsafe operations.

Note: Recompile with -Xlint:unchecked for details.

The code template uses "itemsCount()" not "itemCount()"