When triggering a parameterized job using a build step, default parameters values are not honored when explicitly setting the value of at least one parameter.

To reproduce it:

1. Create a parameterized Workflow job (call it "paramd-job"), with 2 string parameters: A, with default value "A" and B with default value "B" and script echo A; echo B
2. Trigger paramd-job from a second Workflow job using: build job: 'paramd-job', parameters: [[$class: 'StringParameterValue', name: 'A', value: 'Custom value']]

Expected: paramd-job triggered with A="Custom value" and B="B", both values printed in the build log.
Actual: B is not defined. groovy.lang.MissingPropertyException: No such property: B for class: WorkflowScript