feat(eslint-plugin): add rule for new lines after copyright header

projects/eslint-plugin/configs/portal.js

@@ -9,6 +9,7 @@ const config = {
 	extends: [require.resolve('./react')],
 	rules: {
 		'@liferay/portal/deprecation': 'error',
+		'@liferay/portal/empty-line-after-copyright': 'error',
 		'@liferay/portal/no-default-export-from-frontend-js-web': 'error',
 		'@liferay/portal/no-document-cookie': 'error',
 		'@liferay/portal/no-explicit-extend': 'error',

projects/eslint-plugin/rules/portal/index.js

@@ -5,6 +5,7 @@
 
 module.exports = {
 	'portal/deprecation': require('./lib/rules/deprecation'),
+	'portal/empty-line-after-copyright': require('./lib/rules/empty-line-after-copyright'),
 	'portal/no-default-export-from-frontend-js-web': require('./lib/rules/no-default-export-from-frontend-js-web'),
 	'portal/no-document-cookie': require('./lib/rules/no-document-cookie'),
 	'portal/no-explicit-extend': require('./lib/rules/no-explicit-extend'),

projects/eslint-plugin/rules/portal/lib/rules/empty-line-after-copyright.js

@@ -0,0 +1,52 @@
+/**
+ * SPDX-FileCopyrightText: © 2021 Liferay, Inc. <https://liferay.com>
+ * SPDX-License-Identifier: MIT
+ */
+
+const message = 'Expected an empty line after the copyright notice.';
+
+module.exports = {
+	create(context) {
+		return {
+			Program() {
+				const comments = context.getSourceCode().getAllComments();
+
+				const copyrightComment = comments.find((item) =>
+					item.value.match('SPDX-FileCopyrightText:')
+				);
+
+				if (!copyrightComment) {
+					return;
+				}
+
+				const endLine = copyrightComment.loc.end.line;
+
+				const firstNode = context.getSourceCode().ast.body[0];
+
+				if (firstNode && firstNode.loc.start.line === endLine + 1) {
+					context.report({
+						fix: (fixer) => {
+							return fixer.insertTextAfter(
+								copyrightComment,
+								'\n'
+							);
+						},
+						message,
+						node: firstNode,
+					});
+				}
+			},
+		};
+	},
+
+	meta: {
+		docs: {
+			category: 'Best Practices',
+			description: message,
+			recommended: false,
+		},
+		fixable: 'code',
+		schema: [],
+		type: 'problem',
+	},
+};