Yea, looking back at this and what I implemented was not great. Haha. I have refactored the code such that it only references the function and removed all that companion object stuff. Also I removed the complicated tests and just left a simple test that expects given inputs and expected outcomes. Let me know what you think. Thanks

Kotlin Translation kumited. Please review and approve if all is well with thee.

For Kotlin, could you make some changes to the test Class and remove the semicolons and also the unused import import java.util.Random. I noticed that if I copy and paste with the semicolon, some IDEs will think it is a Java Class rather than a Kotlin Class.
I've put the edit below:

import org.junit.Test
import kotlin.test.assertEquals

class OppositeExampleTests {

  @Test fun testFixed() {
    assertEquals(-1, opposite(1))
    assertEquals(0, opposite(0))
    assertEquals(25, opposite(-25))
  }
}

For Java, the method signature should be:

  public static int sumOfAngles(int n) {
      // Code Here
  }

yours is void and won't return anything.
You unit tests should take the format of assertEquals('expected value here', AngleSum.sumOfAngles(3));

Also the parameter should specify the type which is int. currently it's public int nearestSq(n){} when it should be public static int nearestSq(int n){}

Your tests are in the wrong format: org.junit.Assert.assertEquals("expected", "actual");. You have this the other way around.

Your tests are the wrong way round they should follow this format assertArrayEquals(int[] expected, int[] actual);.
Your tests are the other way round in this case:

assertArrayEquals(new String[]{ "tail", "body", "head" },
          WrongEndHead.fixTheMeerkat(new String[]{ "head", "body", "tail" }));

which is not consistent to what you said: You will be given an array which will have three values (tail, body, head). It is your job to re-arrange the array so that the animal is the right way round (head, body, tail).. You're passing the correct values to the fixTheMeerkat() method.