Update File Metadata API for Published dataset should be accessible

[ChengShi-1]

What steps does it take to reproduce the issue?

• In JSF, create a dataset with a file
• test the api, post .../api/v1/files/{fileID}/metadata , works well
• publish the dataset
• test the api, post .../api/v1/files/{fileID}/metadata , 400 error occurs

• When does this issue occur?
  When I use post .../api/v1/files/27/metadata from native api to edit file metadata, if the dataset of the file is published, the result would be a 400 error { "status": "ERROR", "message": "Filename already exists at blob" }(blob is the file name I upload)

• Which page(s) does it occurs on?
  File, update file metadata api

• What happens?

• To whom does it occur (all users, curators, superusers)?
  api users

• What did you expect to happen?
  No matter what the dataset status is, should be able to edit file metadata

Which version of Dataverse are you using?
api

Any related open or closed issues to this bug report?
#IQSS/dataverse-client-javascript#213

Not sure about the size, so randomly put a size tag here, feel free to adjust.

[qqmyers]

Good catch. Looks like this happens when a new draft version is created. The intent is to check the name you're sending in against the names of all other files, but the loop at

dataverse/src/main/java/edu/harvard/iq/dataverse/api/Files.java

Lines 468 to 471 in 1e1bd6d

	for (FileMetadata fileMetadata : fmdList) {
	if (!fileMetadata.equals(df.getFileMetadata())) {
	fmdListMinusCurrentFile.add(fileMetadata);
	}

is trying to remove the filemetadata for the file being changed that is in the published version from the list of all filemetadatas in the new draft version. (Since it isn't in there, the following code finds a file name conflict with the file you're changing.)