Hi I still have a problem with 2.2.45. (2.2.43 works fine)
If I annotate like this in a java library
@NotNull
@Schema(description = "an integer")
private Integer someInteger;

The generated openapi-spec is:
"someInteger": {
"type": "integer",
"format": "int32",
"default": "##default",
"description": "an integer"
}

And the generated code will be:
@jakarta.annotation.Nonnull
private Integer someInteger = ##default;

If I add a default value the problem disappears:
@NotNull
@Schema(description = "an integer", defaultValue = "0")
private Integer someInteger;

@JanneAndersson please see following bugs. They seem to describe your issue

• [Bug]: Problem with ##default and release 2.2.44 #5076
• [Bug]: Another ##default leaks case (version 2.2.44 and 2.2.45): @Parameter + @ArraySchema #5086

@JanneAndersson this test works well for OAS 3.0 and 3.1:

public static class NonNullableInteger {
        @NotNull
        @Schema(description = "an integer")
        private Integer nonNullableInteger;
        public void setNonNullableInteger(Integer nonNullableInteger) {
            this.nonNullableInteger = nonNullableInteger;
        }
    }

If the problem still occurs, please create a new ticket and provide a complete example. Call me in a new issue.
Please ensure that you are working with the latest version 2.2.45.