Only allow integers (whole numbers, including negative values) in Gravity Forms Number field

gf-number-field-integers.php

<?php

/**
 * Force number fields to increment by 1
 */
add_filter( 'gform_field_content', function ( $field_content, $field ) {
	
	if ( 'number' !== $field->type ) {
		return $field_content;
	}
	
	return str_replace( "step='any'", "step='1'", $field_content );

}, 10, 2 );