Redocly custom rule from built-in rule

my-custom-plugin.js

const NamedBooleans = require('./rules/named-booleans');

module.exports = {
  id: 'extras-plugin',
  rules: {
    oas3: {
      'boolean-naming-rules': NamedBooleans,
    }
  }

}

named-booleans.js

// in the rules/ directory
module.exports = NamedBooleans;

// based on https://github.com/Redocly/redocly-cli/blob/main/packages/core/src/rules/oas3/boolean-parameter-prefixes.ts
function NamedBooleans({ suppliedSuffixes}) {
  const suffixes = suppliedSuffixes || ['is', 'has'];
  const regexp = new RegExp(`[A-Z-_](${suffixes.join('|')})$`);
  const wrappedSuffixes = suffixes.map((p) => `\`${p}\``);
  const suffixesString =
    wrappedSuffixes.length === 1
      ? wrappedSuffixes[0]
      : wrappedSuffixes.slice(0, -1).join(', ') + ' or ' + wrappedSuffixes[suffixes.length - 1];

  return {
    Parameter: {
      // the ctx parameter is different than the built-in plugins)
      Schema(schema, ctx, parents) {
        if (schema.type === 'boolean' && !regexp.test(parents.Parameter.name)) {
          ctx.report({
            message: `Boolean parameter \`${parents.Parameter.name}\` should have ${suffixesString} suffix.`,
            // location defined using the ctx parameter
            location: ctx.location.child(['name']),
          });
        }
      },
    },
  };
}

redocly.yaml

extends: []

plugins:
  - './my-custom-plugin.js'

 rules:
  extras-plugin/boolean-naming-rules:
    severity: error
    suppliedSuffixes: ["Enabled", "Indicator"]