[Bug]: incorrect sibling logic when reading type from schema annotation

Author: Mattias-SehlstedtCreated Jul 15, 2026Updated Jul 16, 2026

LabelsBugbacklog

Description of the problem/issue

When defining @Schema(type = ...) on a model that is resolved to OAS 3.1, then the property is always marked as type: string. This is incorrect and it stems from a bug introduced in https://github.com/swagger-api/swagger-core/pull/4970. The issue is this change and more precisely that ctxSchema.type().getClass() will always produce the String class.

Affected Version

2.2.52

Earliest version the bug appears in (if known):
2.2.37

This was discovered in https://github.com/swagger-api/swagger-core/issues/5233 and thus reuses their steps to reproduce.

Steps to Reproduce

java

import io.swagger.v3.core.converter.AnnotatedType;
import io.swagger.v3.core.converter.ModelConverters;
import io.swagger.v3.core.converter.ResolvedSchema;
import io.swagger.v3.core.util.Json31;
import io.swagger.v3.oas.annotations.media.Schema;
import java.math.BigDecimal;

public class Repro {
  enum Freq { DAY, WEEK, MONTH }

  static class Dto {
    @Schema(title = "Inferred") public BigDecimal inferred;         // no explicit type (control)
    @Schema(title = "Amount", type = "number")  public BigDecimal amount;
    @Schema(title = "Count",  type = "integer") public Integer count;
    @Schema(title = "Flag",   type = "boolean") public Boolean flag;
    @Schema(title = "Unit")   public Freq unit;                     // enum (control)
  }

  public static void main(String[] args) {
    ModelConverters converters = new ModelConverters(true); // openapi31 = true
    ResolvedSchema resolved =
        converters.resolveAsResolvedSchema(new AnnotatedType(Dto.class));

    // root cause: scalar type is correct, but the "types" set is ["string"]
    resolved.schema.getProperties().forEach((name, s) ->
        System.out.println(name + " -> getType()=" + s.getType() + " getTypes()=" + s.getTypes()));

    System.out.println(Json31.pretty(resolved.schema));
  }
}

Expected Behavior

json

{
  "properties": {
    "inferred": { "type": "number" },
    "amount":   { "type": "number" },
    "count":    { "type": "integer" },
    "flag":     { "type": "boolean" },
    "unit":     { "type": "string", "enum": ["DAY", "WEEK", "MONTH"] }
  }
}

Actual Behavior

jsonc

{
  "properties": {
    "inferred": { "type": "number" },                                  // OK (inferred, control)
    "amount":   { "type": "string" },                                  // WRONG, declared "number"
    "count":    { "type": "string" },                                  // WRONG, declared "integer"
    "flag":     { "type": "string" },                                  // WRONG, declared "boolean"
    "unit":     { "type": "string", "enum": ["DAY", "WEEK", "MONTH"] }  // OK (enum, control)
  }
}

Logs / Stack Traces

Additional Context

Checklist

I have searched the existing issues and this is not a duplicate.
I have provided sufficient information for maintainers to reproduce the issue.

Source: swagger-api/swagger-core

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