Before being configured a WebClient has several partWriters:

after being configured it doesn't have any:

This prevents multipart files from being serialized by a configured WebClient:
org.springframework.core.codec.CodecException: No suitable writer found for part: input_image
at org.springframework.http.codec.multipart.MultipartHttpMessageWriter.encodePart(MultipartHttpMessageWriter.java:299)
Suppressed: reactor.core.publisher.FluxOnAssembly$OnAssemblyException:
Error has been observed at the following site(s):
|_ checkpoint ⇢ Request to PUT https://[redacted] [DefaultWebClient]
Stack trace:
at org.springframework.http.codec.multipart.MultipartHttpMessageWriter.encodePart(MultipartHttpMessageWriter.java:299)
at org.springframework.http.codec.multipart.MultipartHttpMessageWriter.lambda$encodePartValues$4(MultipartHttpMessageWriter.java:252)
Before being configured a WebClient has several partWriters:


after being configured it doesn't have any:
This prevents multipart files from being serialized by a configured WebClient: