Three new article modules: configuration binding, profiles and config data, Spring AOP

configuration-properties/  @ConfigurationProperties vs @Value on Spring Boot 4.1.1.
  The relaxed-binding matrix is generated by binding each spelling rather than
  transcribed, and re-checked against real processes -- the in-process probe was
  wrong twice before it was right. Records the three findings that came out of it:
  @Value does get relaxed resolution inside Spring Boot (Boot attaches
  ConfigurationPropertySources), the configuration processor silently stops
  generating metadata on JDK 23+ when declared as a plain dependency, and @Valid is
  not what makes nested constraints run.

profiles-and-config/       Precedence, profiles, spring.config.import and config trees.
  /precedence reports every source holding a property in rank order with file and
  line, which turns "my profile file had no effect" into a two-line answer. Also
  pins the counterintuitive one: an imported file outranks the file that imported it.

spring-aop/                Designators, proxy types, and aspects that do not fire.
  One advice per supported designator so the reference table is generated from real
  matches; all fourteen unsupported designators fed to the parser. Two corrections to
  the reference documentation: unsupported designators throw
  UnsupportedPointcutPrimitiveException (extends RuntimeException, not
  IllegalArgumentException), and spring-boot-starter-aop was renamed to
  spring-boot-starter-aspectj in Boot 4.

19 contract tests across the three modules, 15 captured transcripts, all regenerated
by scripts/run-all.sh. Verified on Spring Boot 4.1.1, Spring Framework 7.0.9,
JDK 25.0.4.1.

Co-Authored-By: Claude Opus 5 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01Gip4srpzMwjgoba6uEfbr5

profiles-and-config/scripts/demo-precedence.sh

@@ -0,0 +1,42 @@
+#!/usr/bin/env bash
+# The whole precedence question, asked once with every source set at the same time.
+#
+# demo.greeting is set by application.yaml, by application-prod.yaml, by an environment
+# variable, by a system property and by a command-line argument -- simultaneously. The
+# endpoint reports all of them in order, so the winner is not a matter of opinion.
+set -euo pipefail
+set +m          # no job-control notices ("Killed") in the captured transcript
+cd "$(dirname "$0")/.."
+source scripts/env.sh
+
+{
+  echo "== every source sets demo.greeting at once =="
+  echo
+  echo "\$ DEMO_GREETING=from-environment-variable \\"
+  echo "    java -Ddemo.greeting=from-system-property \\"
+  echo "         -jar $JAR --spring.profiles.active=prod \\"
+  echo "         --demo.greeting=from-command-line-argument"
+  echo
+
+  scripts/stop.sh
+  DEMO_GREETING=from-environment-variable setsid nohup java \
+    -Ddemo.greeting=from-system-property -jar "$JAR" \
+    --spring.profiles.active=prod --demo.greeting=from-command-line-argument \
+    > /tmp/profiles-precedence.log 2>&1 < /dev/null &
+  echo $! > target/app.pid
+  for _ in $(seq 1 60); do
+    curl -s -o /dev/null "http://127.0.0.1:${APP_PORT}/precedence" && break; sleep 1; done
+
+  curl -s "http://127.0.0.1:${APP_PORT}/precedence?name=demo.greeting" | python3 -m json.tool
+  echo
+  echo "== and with the environment variable removed, nothing else changed =="
+  scripts/stop.sh
+  setsid nohup java -Ddemo.greeting=from-system-property -jar "$JAR" \
+    --spring.profiles.active=prod > /tmp/profiles-precedence2.log 2>&1 < /dev/null &
+  echo $! > target/app.pid
+  for _ in $(seq 1 60); do
+    curl -s -o /dev/null "http://127.0.0.1:${APP_PORT}/precedence" && break; sleep 1; done
+  curl -s "http://127.0.0.1:${APP_PORT}/precedence?name=demo.greeting" | python3 -m json.tool
+  scripts/stop.sh
+} > docs/output/01-precedence.txt 2>&1
+cat docs/output/01-precedence.txt