Resource pattern collection identifiers

This rule enforces that messages that have a google.api.resource annotation have properly formatted collection identifiers in each pattern, as described in AIP-122.

Details

This rule scans messages with a google.api.resource annotation, and validates the format of pattern collection identifiers, specifically that they are in lowerCamelCase form and must start with a lowercase letter.

Examples

Incorrect code for this rule:

// Incorrect.
message Book {
  option (google.api.resource) = {
    type: "library.googleapis.com/Book"
    // Collection identifiers must be lowerCamelCase.
    pattern: "Publishers/{publisher}/Books/{book}"
  };
  string name = 1;
}

// Incorrect.
message Book {
  option (google.api.resource) = {
    type: "library.googleapis.com/Book"
    // Collection identifiers must begin with a lower-cased letter.
    pattern: "/publishers/{publisher}/Books/{book}"
  };
  string name = 1;
}

Correct code for this rule:

// Correct.
message Book {
  option (google.api.resource) = {
    type: "library.googleapis.com/Book"
    pattern: "publishers/{publisher}/books/{book}"
  };
  string name = 1;
}

Disabling

If you need to violate this rule, use a leading comment above the message.

// (-- api-linter: core::0122::resource-collection-identifiers=disabled
//     aip.dev/not-precedent: We need to do this because reasons. --)
message Book {
  option (google.api.resource) = {
    type: "library.googleapis.com/Book"
    pattern: "Publishers/{publisher}/Books/{book}"
  };
  string name = 1;
}

If you need to violate this rule for an entire file, place the comment at the top of the file.