Terraform update only a cloud function from a bunch - google-cloud-platform

Question

I have a Terraform project that allows to create multiple cloud functions.
I know that if I change the name of the google_storage_bucket_object related to the function itself, terraform will see the difference of the zip name and redeploy the cloud function.
My question is, there is a way to obtain the same behaviour, but only with the cloud functions that have been changed?
resource "google_storage_bucket_object" "zip_file" {
# Append file MD5 to force bucket to be recreated
name = "${local.filename}#${data.archive_file.source.output_md5}"
bucket = var.bucket.name
source = data.archive_file.source.output_path
}
# Create Java Cloud Function
resource "google_cloudfunctions_function" "java_function" {
name = var.function_name
runtime = var.runtime
available_memory_mb = var.memory
source_archive_bucket = var.bucket.name
source_archive_object = google_storage_bucket_object.zip_file.name
timeout = 120
entry_point = var.function_entry_point
event_trigger {
event_type = var.event_trigger.event_type
resource = var.event_trigger.resource
}
environment_variables = {
PROJECT_ID = var.env_project_id
SECRET_MAIL_PASSWORD = var.env_mail_password
}
timeouts {
create = "60m"
}
}
By appending MD5 every cloud functions will result in a different zip file name, so terraform will re-deploy every of them and I found that without the MD5, Terraform will not see any changes to deploy.
If I have changed some code only inside a function, how can I tell to Terraform to re-deploy only it (so for example to change only its zip file name)?
I hope my question is clear and I want to thank you everyone who tries to help me!