The code above isn't formatted properly and can't be considered as "Best Practices".

Google(https://google.github.io/styleguide/javaguide.html#s4.6.2-horizontal-whitespace) advises to have whitespaces "On both sides of any binary or ternary operator."

Oracle(https://www.oracle.com/technetwork/java/codeconventions-150003.pdf) advises the same: "All binary operators except . should be separated from their operands by spaces."

Not applicable anymore

Not an issue ;-)

Not an issue ;-)

(Also you can see example tests)

Not an issue ;-)

Good kata, but you should change the name, as this is not what camel case is.

the text of the kata doesn't give enough information,even it has many cases

My understanding of Camel Case is that it can also start with a lowercase letter (depending on usage, like an object vs. a class), so I was a little confused at first when my solution was rejected. I figured it out, though :)

As was previously stated, this kata should say that it expects the first character of the returning string to always be uppercase.

The kata should mention that it expects the forst charecter to be uppercase

yep) agree
removed "body" code )

I would provide an empty method body as a starting point. Now you're already providing half the solution and possibly pushing people towards a certain solution.

How could this have possibly worked? Are there no testcases for this kata?

ok

The description could be a little better on this kata. For example, the kata neglects to mention that it expects the string to start as uppercase.

Otherwise, I like it a lot.