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<?php
/**
 * Gravity Perks // GP Post Content Merge Tags // Support Plus Signs when Populating a Form
 * https://gravitywiz.com/documentation/gravity-forms-post-content-merge-tags/
 */
add_filter( 'shortcode_atts_gravityforms', function( $out, $pairs, $atts, $shortcode ) {

	if( isset( $out['field_values'] ) ) {
		$out['field_values'] = str_replace( '+', '%2B', $out['field_values'] );
	}

	return $out;
}, 10, 4 );