Set reviewer interest filed mandatory

Hello
How I can set the filed “interest” in “create reviewer form” as mandatory , by same way to add keywords in submission form.

/lib/pkp/templates/controllers/grid/users/reviewer/form/createReviewerForm.tpl

{fbvFormSection title=“manager.reviewerSearch.interests” for=“interests”}
{fbvElement type=“interests” id=“interests” interests=$interests}
{/fbvFormSection}

/lib/pkp/templates/submission/submissionMetadataFormFields.tpl

{fbvFormSection label=“common.keywords” required=$keywordsRequired}
{fbvElement type=“keyword” label=“submission.keyword.tip” id=“keywords” multilingual=true current=$keywords disabled=$readOnly required=$keywordsRequired}
{/fbvFormSection}

**Application Version - e.g., OJS 3.2.0.3