Closes #3550

Since v0.90, adding @angular/common to the plugin list generates nothing — both httpRequests and httpResources silently default to disabled. Additionally, explicitly setting httpResources: 'flat' crashes with Error: Symbol is not resolved to a node because the resource implementation references request symbols that don't exist when httpRequests is disabled.

Root cause

In resolveHttpRequests and resolveHttpResources, undefined input (user omitted the option) falls into the !input branch and resolves to { enabled: false }, overriding defaultValue.enabled: true:

// undefined → !input is true → { enabled: Boolean(undefined) } → { enabled: false }
} else if (typeof input === 'boolean' || !input) {
  input = { enabled: Boolean(input) };
}

Fix

Separate the undefined case so it passes an empty object and lets context.valueToObject apply all defaults:

} else if (typeof input === 'boolean') {
  input = { enabled: input };
} else if (!input) {
  input = {};  // undefined → use defaults → enabled: true, strategy: 'flat'
}

This also resolves the httpResources: 'flat' crash: when httpRequests is not specified it now defaults to enabled, providing the request symbols that httpResources depends on.

Changes

• httpRequests/config.ts — fix undefined input treated as false
• httpResources/config.ts — same fix
• Test snapshots — add missing @angular/common.gen.ts output for the default scenario across all three OpenAPI versions (2.0.x, 3.0.x, 3.1.x)