2.9.0 NumberFormatException when generation swagger.json doc breaking vendor extensions

• What version of the library are you using: 2.9.0

What kind of issue is this?

• Bug report

So something sneaked into the 2.9.0 version which breaks proper generation of the swagger.json definition. I will try to be as elaborate as possible.

Since 2.9.0 scalarExample has been introduced in springfox.documentation.builders.ParameterBuilder.java. The ParameterBuilder scalarExample(Object scalarExample) method uses the following fallback method this.scalarExample = defaultIfAbsent(scalarExample, this.scalarExample); to decide to go for a given example or use the default one, which is null.

When I debug how the builder method is invoked , I always see the scalarExample argument being set to an empty string eg. "". Tracing things back I bumped into io.swagger.annotations.ApiParam which has its default value set to that empty string. String example() default "";. So this seems like a mismatch between what the builder expects and what is actually passed. The defaultIfAbsent method will always pick the empty string as it never will be null.

So the server runs but when I request the swagger.json via http://{server}/v2/api-docs I see a nasty NumberFormatException being thrown. This happens in io.swagger.models.parameters.AbstractSerializableParameter but it is due to the empty string being set as scalarExample. It tries to parse it via Long.valueOf but this is clearly not a good idea 😁

The code in that class looks like

@JsonProperty("x-example")
    public Object getExample() {
        if (example == null) {
            return null;
        }
        try {
            if (BaseIntegerProperty.TYPE.equals(type)) {
                return Long.valueOf(example);
            } else if (DecimalProperty.TYPE.equals(type)) {
                return Double.valueOf(example);
            } else if (BooleanProperty.TYPE.equals(type)) {
                if ("true".equalsIgnoreCase(example) || "false".equalsIgnoreCase(defaultValue)) {
                    return Boolean.valueOf(example);
                }
            }
        } catch (NumberFormatException e) {
            LOGGER.warn(String.format("Illegal DefaultValue %s for parameter type %s", defaultValue, type), e);
        }
        return example;
    }

My suggestion is to take empty strings into account in the defaultIfAbsent method

[borcherspm]

If you have any request/response classes that are being used as models in your swagger, I figured out what was causing the errors for me. I had an Integer field that had the annotation ApiModelProperty. If I add the example = "1" to the annotation the NumberFormatException goes away.

@ApiModelProperty(value = "The page number to return.", required = true, example = "1")
private Integer page;

[stale[bot]]

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