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

configuration-properties/scripts/demo-value-vs-binding.sh

@@ -0,0 +1,34 @@
+#!/usr/bin/env bash
+# Side by side: what the binder produced and what @Value produced, from one running process.
+set -euo pipefail
+cd "$(dirname "$0")/.."
+source scripts/env.sh
+{
+  echo "== @ConfigurationProperties vs @Value, same application, same application.yaml =="
+  echo
+  scripts/run.sh > /dev/null
+  echo "\$ curl -s localhost:8080/diag/bound"
+  curl -s "http://127.0.0.1:${APP_PORT}/diag/bound" | python3 -m json.tool
+  echo
+  echo "demo.mail.recipients is a YAML block list. The binder produced both elements."
+  echo "@Value produced an empty list -- placeholder resolution has no concept of a YAML"
+  echo "sequence, so \${demo.mail.recipients:} fell through to its own empty default."
+  echo
+  echo "== the same list written as a comma-separated string, at higher precedence =="
+  scripts/run.sh "" --demo.mail.recipients=x@e.com,y@e.com,z@e.com > /dev/null
+  echo "\$ ./scripts/run.sh \"\" --demo.mail.recipients=x@e.com,y@e.com,z@e.com"
+  curl -s "http://127.0.0.1:${APP_PORT}/diag/bound" \
+    | python3 -c 'import json,sys; d=json.load(sys.stdin); print("  binder :", d["mail"]["recipients"]); print("  @Value :", d["fromValueAnnotation"]["recipients"])'
+  echo
+  echo "Both see it. A comma-separated string is the one list shape @Value understands, and"
+  echo "the command-line source outranks the YAML file for the binder as well."
+  echo
+  echo "== where did that value come from? =="
+  echo "\$ curl -s 'localhost:8080/diag/origin?name=demo.mail.recipients'"
+  curl -s "http://127.0.0.1:${APP_PORT}/diag/origin?name=demo.mail.recipients" | python3 -m json.tool
+  echo
+  echo "\$ curl -s 'localhost:8080/diag/origin?name=demo.mail.host'"
+  curl -s "http://127.0.0.1:${APP_PORT}/diag/origin?name=demo.mail.host" | python3 -m json.tool
+  scripts/stop.sh
+} > docs/output/03-value-vs-binding.txt 2>&1
+cat docs/output/03-value-vs-binding.txt