Implicit Parameters
Implicit parameters are parameters that the Mule runtime engine automatically injects without requiring configuration from the application developer. Examples include StreamingHelper, ComponentLocation, and CorrelationInfo. These parameters don’t appear in the Extension Model.
Implicit Parameter Types from org.mule.sdk.api
Starting with Mule 4.5, the runtime automatically treats parameters with types from org.mule.sdk.api and its subpackages as implicit, enabling forward compatibility for new implicit parameter types.
When you use a new implicit parameter type that was introduced in a later Mule version:
-
On runtimes that support the type, the parameter is injected normally
-
On earlier Mule runtime versions that don’t recognize the type, the parameter resolves to
nulland the runtime treats the parameter as implicit, meaning it doesn’t appear in the Extension Model and can’t be configured by the application developer.
Handle Null Values
Implicit parameters from org.mule.sdk.api resolve to null on earlier Mule runtime versions. Your code must handle this possibility:
import org.mule.sdk.api.runtime.SomeNewHelper;
public class MyOperations {
public void myOperation(String input, SomeNewHelper helper) {
if (helper != null) {
// Use the helper on runtimes that support it
helper.doSomething();
} else {
// Fallback for older runtimes
}
}
}
If the implicit parameter is essential to your operation and no fallback is possible, annotate the operation with @MinMuleVersion to restrict it to runtimes that support the parameter type.
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