RFR: 8249783: Simplify DerValue and DerInputStream [v2]

[Valerie Peng]

On Sat, 26 Sep 2020 00:52:38 GMT, Weijun Wang <weijun at openjdk.org> wrote:

>> src/java.base/share/classes/sun/security/util/DerValue.java line 1154:
>> 
>>> 1152:      * @return a new DerValue
>>> 1153:      */
>>> 1154:     public DerValue withTag(byte newTag) {
>> 
>> Seems like a somewhat dangerous method. The value may not match the new tag? The caller is expected to know what it's
>> doing?
>
> I intend to use it to turn back IMPLICIT element to its original tag, otherwise getXyz() calls would fail because they
> are checking the tag. In the old design, checking the tag (in DerValue) and reading the value (in DerInputBuffer) are
> separated but now they are in a single method (in DerValue).  The caller pattern should always look like
> `withTag(INTEGER).getInteger()`.

Hmm, I see, maybe add more comments then.

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PR: https://git.openjdk.java.net/jdk/pull/232