Describe the bug

In our open source project reqstool we have several JSON Schemas. We would like to use datamode-code-generator to generate pydantic v2 code, but the code does not get generated correctly.

Our schemas have been validated with: check-jsonschema --verbose --schemafile "https://json-schema.org/draft/2020-12/schema" <schema_folder>/*

However, it seems as if patternProperties in JSON Schemas are not handled properly.

To Reproduce

Example schema:

All schemas are available here: https://github.com/Luftfartsverket/reqstool-client/tree/main/src/reqstool/resources/schemas/v1

The requirements.schema.json is the most advanced but it does not use pattternProperties.

An example to use is: annotations.schema.json where there is:

note: This particular case does not need to use patternProperties since the two properties implementations and tests and known before runtime.

  "$defs": {
        "requirement_annotations": {
            "type": "object",
            "additionalProperties": false,
            "patternProperties": {
                "^implementations": {
                    "type": "object",
                    "$ref": "#/$defs/annotation",
                    "description": "requirement annotation used in implementation"
                },
                "^tests": {
                    "type": "object",
                    "$ref": "#/$defs/annotation",
                    "description": "requirement annotation used in test"
                }
            }
        }

Used commandline:

$ DIR=. find $DIR -type f -name '*.schema.json' -exec sh -c 'base_name=$(basename "{}" .schema.json); datamodel-codegen --input "{}" --input-file-type jsonschema --output "$DIR/$base_name.py"   --output-model-type pydantic_v2.BaseModel --use-annotated   --use-standard-collections --capitalize-enum-members --target-python-version 3.10 --use-schema-description --wrap-string-literal --use-double-quotes --use-field-description --snake-case-field ' \;

Expected behavior
A clear and concise description of what you expected to happen.

Version:

• OS: Ubuntu 22.04 LTS
• Python version: Python 3.10.12
• datamodel-code-generator version: 0.25.3

Additional context
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