[BUG] combining typeMappings with default can create broken Pojo artefact

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• Have you provided a full/minimal spec to reproduce the issue?
• Have you validated the input using an OpenAPI validator (example)?
• Have you tested with the latest master to confirm the issue still exists?
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• What's the actual output vs expected output?
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Description

Consider the following Object definition in a swagger:

"OdbcConnection": {
  "type": "object",
  "properties": {
    "ConnectionString": {
      "type": "string",
      "nullable": true
    },
    "ConnectionTimeout": {
      "type": "integer",
      "format": "int32",
      "default": 15
    }
  },
  "additionalProperties": false
}

We have a pattern where we try to work with longs so I configure my execution to translate all int to long:
<typeMappings>integer=Long,int=Long</typeMappings>

This works well, however in the rendered POJO I get a variable declaration for ConnectionTimeout that attempts to assign an int to a long which does not compile:

  public static final String JSON_PROPERTY_CONNECTION_TIMEOUT = "ConnectionTimeout";
  private Long connectionTimeout = 15;

If I manually modify the swagger to use int64 instead of int32 the 'l' character is appended to the default value correctly.

I believe the toDefaultValue method of the AbstractJavaCodegen needs an addition to account for this situation

openapi-generator version

OpenAPI declaration file content or url

Generation Details

Steps to reproduce

Related issues/PRs

Suggest a fix

Start in AbstractJavaCodegen.toDefaultValue and reproduce the issue with the OdbcConnection schema and integer=Long,int=Long type mappings. Verify that the generated Java POJO handles the integer default correctly for the mapped Long field and remains compilable.