Polish a few issue identified when adding checkstyle to the
build. Although checkstyle is not enforcing rules on tests,
these are a few minor changes that are still worth making.
Issue: SPR-16968
With this change the code generation for method and property
references is modified to include branching logic in the
case of null safe dereferencing (?.). This is complicated
by the possible usage of primitives on the left hand side
of the dereference. To cope with this case primitives are
promoted to boxed types when this situation occurs enabling
null to be passed as a possible result.
Issue: SPR-16489
This commits extends nullability declarations to the field level, formalizing the interaction between methods and their underlying fields and therefore avoiding any nullability mismatch.
Issue: SPR-15720
Beyond just formally declaring the current behavior, this revision actually enforces non-null behavior in selected signatures now, not tolerating null values anymore when not explicitly documented. It also changes some utility methods with historic null-in/null-out tolerance towards enforced non-null return values, making them a proper citizen in non-null assignments.
Some issues are left as to-do: in particular a thorough revision of spring-test, and a few tests with unclear failures (ignored as "TODO: NULLABLE") to be sorted out in a follow-up commit.
Issue: SPR-15540
Until this change a single classloader was used to load
all compiled SpEL expressions. This meant in a context where an
expression was repeatedly flipping between compiled and interpreted
mode (which can happen if in MIXED mode compilation and changing
the context around the evaluation) the classloader would continually
load a new compiled version but not orphan the old compiled version.
This eventually uses up all the memory as the number of classes
is ever increasing.
With this change classloaders are used to load 100 compiled
expressions. The 101st will be loaded by a new one. Orphaning the
old classloader means if an expression is ever recompiled there
is more likely to be no anchored references left to the older
compiled form and it can be GC'd. In the MIXED situation above it
should help alleviate the problem of older classes never being
candidates for GC.
Issue: SPR-15460
Without this fix the compiled version of elvis
actual behaved differently to the interpreted version
if the value being queried was an empty string. This
is now fixed. It also now correctly handles the
query value being a primitive and addresses the
findings of SPR-15192 where some type inferencing
logic was trying to be too clever, that code has
been deleted.
Issue: SPR-15192
Juergen Hoeller
Spring Operator
Rossen Stoyanchev
Stephane Nicoll
igor-suhorukov
Hanope
Andy Clement
Phillip Webb
Christoph Dreis