Add number type conversion validation to ensure proper casting between numeric types

[mcruzdev]

Changes

• Implement convertNumber method in AbstractWorkflowModel to handle conversions between numeric types
• Fix issue where asNumber() returned incompatible Number types without proper casting
• Ensure type safety when converting workflow model outputs to specific numeric types

Closes #1200

[Copilot]

Pull request overview

This PR adds a convertNumber private method to AbstractWorkflowModel to properly dispatch numeric type conversions when as(Class<T>) is called with a Number-derived class (previously returning whatever asNumber() produced, which could cause a ClassCastException at the call site). It also adds a comprehensive suite of integration tests covering several primitive wrapper conversions (Long↔Integer, Double↔Integer, Float↔Double, Short↔Integer, Byte↔Integer).

Changes:

• AbstractWorkflowModel.java: Replace the raw asNumber() call with asNumber().map(num -> convertNumber(num, clazz)), and add the convertNumber dispatch method.
• WorkflowNumberConversionTest.java: New integration test class exercising seven conversion scenarios.

Reviewed changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
impl/core/src/main/java/io/serverlessworkflow/impl/AbstractWorkflowModel.java	Adds convertNumber method and wires it into as() for Number-typed requests
impl/test/src/test/java/io/serverlessworkflow/impl/test/WorkflowNumberConversionTest.java	Integration tests for numeric type conversions across multiple primitive wrapper types

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[Copilot]

The convertNumber method does not handle BigDecimal or BigInteger types, even though both are Number subclasses supported by the codebase (as evidenced by JacksonModelFactory.from(Number) and JsonUtils handling them). When as(BigDecimal.class) or as(BigInteger.class) is called, execution reaches the else { return (T) num; } branch. Because asNumber() in JacksonModel always returns a Long (via node.asLong()), this unchecked cast will produce a ClassCastException at the call site. The convertNumber method should explicitly handle BigDecimal and BigInteger — for example, by calling new BigDecimal(num.toString()) or BigDecimal.valueOf(num.longValue()) for BigDecimal, and BigInteger.valueOf(num.longValue()) for BigInteger.

[fjtirado]

I think we need to handle this differently, rather than using the asNumber public interface method, add a new protected method here asNumber(Class<?> targetNumberClass) and implement it on the children classes.

That way, you can use JsonNode.asLong, asInt methods in JakcsonModel and copy this implementation to JavaModel. The approach you took implies two conversions: the one performed by asNumber (in JavaModel is straightforward, but in Jackson it is not) and the one performed by this method. It is more efficient to have one in the children class.

[fjtirado]

here is whereasNumber(class)method should be invoked