@dropbox/sign Node SDK uses deprecated util.isArray API causing deprecation warnings #520

Description

The @dropbox/sign package (version 1.10.0) bundles form-data directly into its dist file (dist/api.js), and the bundled code uses the deprecated util.isArray API, which causes Node.js deprecation warnings.

Steps to Reproduce

1. Install @dropbox/sign@1.10.0
2. Use the SDK to create a signature request (e.g., signatureRequestSend)
3. Run the code with Node.js 18+ (or any version that shows deprecation warnings)

Expected Behavior

No deprecation warnings should appear.

Actual Behavior

The following deprecation warning appears:

(node:xxxxx) [DEP0044] DeprecationWarning: The util.isArray API is deprecated. Please use Array.isArray() instead.
at FormData3.append (/path/to/node_modules/@dropbox/sign/dist/api.js:9176:17)

Location

The issue is in the bundled form-data code within dist/api.js at line 9176:

if (util3.isArray(value)) {

Suggested Fix

Replace util3.isArray(value) with Array.isArray(value) in the bundled code. This matches the fix that was already applied in the form-data package itself (see form-data/form-data#567).

Additional Context

• The form-data package itself has been fixed (version 4.0.5+ uses Array.isArray)
• However, since @dropbox/sign bundles form-data directly, updating the form-data dependency doesn't resolve the issue
• This is a non-breaking change that only affects the deprecation warning

Environment

• @dropbox/sign: 1.10.0
• Node.js: 18+ (tested on v18.20.4 and v22+)
• OS: macOS, Debian