Add missing bounds check to deleteCharAt

[mikezhang1234567890]

For StringBuilder and StringBuffer
Add tests for deleteCharAt with out of bound indices.

Fixes #15897

Tested internally here running JCL_Test_SE80

[pshipton]

jenkins test sanity,extended,sanity.openjdk alinux64 jdk8

[keithc-ca]

delete(int start, int end) doesn't appear to match its documented behavior; perhaps all that is needed (e.g. in StringBuffer) is to remove this:

    if (end > currentLength) {
        end = currentLength;
    }

[mikezhang1234567890]

In this case, I think our doc is wrong, last condition to throw the exception should be start > length() instead of end > length().

[pshipton]

Early PR build for reference https://openj9-jenkins.osuosl.org/view/Pull%20Requests/job/PullRequest-OpenJ9/2761/

[keithc-ca]

In this case, I think our doc is wrong, last condition to throw the exception should be start > length() instead of end > length().

I think the documentation is correct. It might be better written as three {@code} blocks instead of two.

[mikezhang1234567890]

Updated the docs for delete as well to hopefully make things clearer. Can you take another look please @keithc-ca ?

[keithc-ca]

jenkins test sanity alinux64 jdk8

[pshipton]

I'm inclined to include this in the 0.35 release since it fixes a bug / user problem, the fix appears low risk, and we haven't yet done the M2 build for jdk8. @keithc-ca thoughts?

[keithc-ca]

I'm inclined to include this in the 0.35 release since it fixes a bug / user problem, the fix appears low risk, and we haven't yet done the M2 build for jdk8.

I agree.

[pshipton]

@mikezhang1234567890 please create a PR against the 0.35 branch.