fix: apply explicit @Schema(type) to the types set under OpenAPI 3.1

[forhadmethun]

Description

Under OpenAPI 3.1, an explicit @Schema(type = ...) was applied via the legacy scalar setType(), while the 3.1 serializer reads the types set. The set kept its default ("string"), so number / integer / boolean fields were rendered as string. This change populates the types set when openapi31 is enabled, mirroring the handling of the plural types() attribute directly below.

AnnotationsUtils.getSchemaFromAnnotation:

if (StringUtils.isNotBlank(schema.type())) {
    if (openapi31) {
        schemaObject.setTypes(new LinkedHashSet<>(Arrays.asList(schema.type())));
    } else {
        schemaObject.setType(schema.type());
    }
}

Before / After (OpenAPI 3.1) — given @Schema(type = "number") BigDecimal amount;:

• Before: amount: { type: "string" }
• After: amount: { type: "number" }

This is a bug fix. It is distinct from #5061 / #5062 (numeric example serialization); it concerns the property type and reproduces with no example present. Fields relying on type inference (no explicit type) were already correct.

Fixes: #5233

Type of Change

• 🐛 Bug fix
• ✨ New feature
• ♻️ Refactor (non-breaking change)
• 🧪 Tests
• 📝 Documentation
• 🧹 Chore (build or tooling)

Checklist

• I have added/updated tests as needed
• I have added/updated documentation where applicable
• The PR title is descriptive
• The code builds and passes tests locally
• I have linked related issues (if any)

Screenshots / Additional Context

Added io.swagger.v3.core.resolving.v31.Ticket5233Test, asserting that explicit number / integer / boolean types land in the types set under OpenAPI 3.1, with inferred-type and enum properties as controls. The full swagger-core module test suite passes locally (721 tests, 0 failures).