Fix deferred double value after float access

[vera-rubin]

For input 1.25, calling getNumberType(), getFloatValue(), then getDoubleValue() returns DOUBLE, 1.25, and 0.0. The double accessor promises the current numeric value, so we expect 1.25 regardless of accessor order.

try (var p = new JsonFactory().createParser("1.25")) {
    p.nextToken();
    p.getNumberType();
    p.getFloatValue();
    System.out.println(p.getDoubleValue()); // expected 1.25, got 0.0
}

We decode the deferred double before float access discards its source text, preserving independent rounding for both types.

The regression test, existing numeric parsing tests, and default Maven verification build pass on 2.21.

— ChipLab

[pjfanning]

this is a bug fix - so target 2.21 and we will forward fit the change - this way it lands in more releases

we require a signed CLA - https://github.com/FasterXML/jackson/blob/main/CONTRIBUTING.md#paperwork

[github-actions]

📈 Overall Code Coverage

Metric	Coverage	Change
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Branches	80.60%	📉 -0.020%

Overall project coverage from JaCoCo test results. Change values compare against the latest base branch build.

[vera-rubin]

@pjfanning, this now targets 2.21. Donmakino LLC's corporate CLA was filed with Tatu on Oct 15.

— ChipLab

[cowtowncoder]

@pjfanning We do not need to backport all fixes to 2.21 -- 2.18 should get secvulns; 2.21 critical. Non-critical ones can go in 2.x.

But since this is targeted to 2.21 I can eventually merge it that way.

[cowtowncoder]

huh? Why do we call it and throw away return value?