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/docs/output/03-value-vs-binding.txt

@@ -0,0 +1,79 @@
+== @ConfigurationProperties vs @Value, same application, same application.yaml ==
+
+$ curl -s localhost:8080/diag/bound
+{
+    "mail": {
+        "host": "smtp.example.com",
+        "port": 587,
+        "timeout": "PT45S",
+        "retries": {
+            "maxAttempts": 5,
+            "backoff": "PT1.5S"
+        },
+        "recipients": [
+            "ops@example.com",
+            "oncall@example.com"
+        ],
+        "headers": {
+            "X-Env": "demo",
+            "X-Team": "platform"
+        }
+    },
+    "validated": {
+        "name": "demo-service",
+        "port": 8443,
+        "endpoint": "https://api.example.com",
+        "pool": {
+            "size": 25
+        }
+    },
+    "fromValueAnnotation": {
+        "host": "smtp.example.com",
+        "port": 587,
+        "timeout": "PT45S",
+        "recipients": [],
+        "poolSize": 25,
+        "computedThreads": 4
+    }
+}
+
+demo.mail.recipients is a YAML block list. The binder produced both elements.
+@Value produced an empty list -- placeholder resolution has no concept of a YAML
+sequence, so ${demo.mail.recipients:} fell through to its own empty default.
+
+== the same list written as a comma-separated string, at higher precedence ==
+$ ./scripts/run.sh "" --demo.mail.recipients=x@e.com,y@e.com,z@e.com
+  binder : ['x@e.com', 'y@e.com', 'z@e.com']
+  @Value : ['x@e.com', 'y@e.com', 'z@e.com']
+
+Both see it. A comma-separated string is the one list shape @Value understands, and
+the command-line source outranks the YAML file for the binder as well.
+
+== where did that value come from? ==
+$ curl -s 'localhost:8080/diag/origin?name=demo.mail.recipients'
+{
+    "property": "demo.mail.recipients",
+    "effectiveValue": "x@e.com,y@e.com,z@e.com",
+    "candidatesInPrecedenceOrder": [
+        {
+            "source": "SimpleCommandLinePropertySource {name='commandLineArgs'}",
+            "value": "x@e.com,y@e.com,z@e.com",
+            "origin": "\"demo.mail.recipients\" from property source \"commandLineArgs\""
+        }
+    ],
+    "shadowedBy": null
+}
+
+$ curl -s 'localhost:8080/diag/origin?name=demo.mail.host'
+{
+    "property": "demo.mail.host",
+    "effectiveValue": "smtp.example.com",
+    "candidatesInPrecedenceOrder": [
+        {
+            "source": "OriginTrackedMapPropertySource {name='Config resource 'class path resource [application.yaml]' via location 'optional:classpath:/''}",
+            "value": "smtp.example.com",
+            "origin": "class path resource [application.yaml] from configuration-properties-1.0.0.jar - 15:11"
+        }
+    ],
+    "shadowedBy": null
+}