It would be easier to review and apply this patch if it was broken down to pieces based on the different types of changes.
See below for a list of the changes I'd rather not apply. Other changes seem reasonable enough, though it's debatable whether changing working code for no functional reason is wise as there's always the chance of accidentally introducing an error. Note that the use of foreach loops needs to wait until we switch to Java 5.
> Changing single character string literals to character literals in string concatenations.
The benefit is insignificant and the drawback is added conceptual complexity (why are some parts of the expression strings and other characters). Also, in expressions where other parts are variables, there is no syntactical hint that it's a string concatenation expression instead of an integer sum.
> Introducing an initial size constant to collection constructors where the expected size is known.
The benefit is in most cases insignificant and the drawback is the introduction of magic numbers in the code. Note that in specific cases this might give real-world performance or memory improvements, but those cases are better covered in separate issues with more detailed analysis.
> Clearing an existing collection instead of replacing it with a newly allocated one.
Again, the benefit is typically insignificant, but as a drawback an immutable collection may become mutable. What if some other code is still concurrently iterating the collection? Perhaps the static analyzer has taken this into account, but will a future programmer that wants to modify the class?