<i18n dev> RFR: 8314604: j.text.DecimalFormat behavior regarding patterns is not clear

[Justin Lu]

Please review this PR and [CSR](https://bugs.openjdk.org/browse/JDK-8314607) which clarifies the behavior of patterns  in regards to the max integer digits in j.text.DecimalFormat.

The current specification (of `applyPattern`) states that patterns do not set the value of max integer digits. This is incorrect, these methods/constructors do set a value for the max integer digits. If the pattern is in scientific notation, the max integer digits value is derived from the pattern. Otherwise, the pattern is ignored, and the limit is set to `Integer.MAX_VALUE`.

See below,

DecimalFormat df = new DecimalFormat();
df.applyPattern("000.000E0");
df.getMaximumIntegerDigits(); //  ==> 3
df.applyPattern("000.000");
df.getMaximumIntegerDigits(); // ==> 2147483647

DecimalFormat df = new DecimalFormat("000.000");
df.getMaximumIntegerDigits(); // ==> 2147483647
DecimalFormat df = new DecimalFormat("000.000E0");
df.getMaximumIntegerDigits(); // ==> 3


Method descriptions should be fixed, and the relevant constructors need to mention the behavior as well.

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Commit messages:
 - Include constructors
 - Re-clarify spec
 - Init

Changes: https://git.openjdk.org/jdk/pull/15349/files
 Webrev: https://webrevs.openjdk.org/?repo=jdk&pr=15349&range=00
  Issue: https://bugs.openjdk.org/browse/JDK-8314604
  Stats: 28 lines in 1 file changed: 22 ins; 0 del; 6 mod
  Patch: https://git.openjdk.org/jdk/pull/15349.diff
  Fetch: git fetch https://git.openjdk.org/jdk.git pull/15349/head:pull/15349

PR: https://git.openjdk.org/jdk/pull/15349