Groovy check rtps for comma and throw error

Summary:

I am looking to add logic to an existing Groovy rule we have that adds dynamic children to our projects hierarchy. I need to add logic that checks the rtps.rtp_Project_Name for commas and throws an error if there is a comma in the string. I tried adding the following but it is throwing a validation error.

// Check for commas in the new project name
if (rtps.rtp_Project_Name.contains(",")) {
throwVetoException("Project name cannot contain commas.")
}

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