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/05-metadata-generation.txt

@@ -0,0 +1,68 @@
+== is the annotation processor discovered? ==
+
+openjdk version "25.0.4.1" 2026-08-18 LTS
+processor jar: spring-boot-configuration-processor-4.1.1.jar
+
+A) processor on the classpath, javac defaults -- what an <optional> dependency gives you
+$ javac -cp <deps>:spring-boot-configuration-processor.jar -d a $SOURCES
+   spring-configuration-metadata.json files produced: 0
+
+B) identical, plus -proc:full
+$ javac -proc:full -cp <deps>:spring-boot-configuration-processor.jar -d b $SOURCES
+   spring-configuration-metadata.json files produced: 1
+
+Both compilations succeed. Only one of them has metadata.
+
+== what this project's pom does instead ==
+The processor is declared as an <annotationProcessorPath> on maven-compiler-plugin,
+which puts it on javac's --processor-path where discovery is not disabled:
+
+$ mvn clean package && ls target/classes/META-INF/
+spring-configuration-metadata.json
+
+== the generated metadata, first entries ==
+{
+    "groups": [
+        {
+            "name": "demo.mail",
+            "type": "com.ankurm.configprops.props.MailProperties",
+            "sourceType": "com.ankurm.configprops.props.MailProperties"
+        },
+        {
+            "name": "demo.mail.retries",
+            "type": "com.ankurm.configprops.props.MailProperties$RetryProperties",
+            "sourceType": "com.ankurm.configprops.props.MailProperties",
+            "sourceMethod": "retries()"
+        },
+        {
+            "name": "demo.relaxed",
+            "type": "com.ankurm.configprops.props.RelaxedProperties",
+            "sourceType": "com.ankurm.configprops.props.RelaxedProperties"
+        },
+        {
+            "name": "demo.validated",
+            "type": "com.ankurm.configprops.props.ValidatedProperties",
+            "sourceType": "com.ankurm.configprops.props.ValidatedProperties"
+        },
+        {
+            "name": "demo.validated.pool",
+            "type": "com.ankurm.configprops.props.ValidatedProperties$Pool",
+            "sourceType": "com.ankurm.configprops.props.ValidatedProperties",
+            "sourceMethod": "pool()"
+        }
+    ],
+    "properties": [
+        {
+            "name": "demo.mail.headers",
+            "type": "java.util.Map<java.lang.String,java.lang.String>",
+            "description": "Bound from arbitrary sub-keys under {@code demo.mail.headers.*}.",
+            "sourceType": "com.ankurm.configprops.props.MailProperties"
+        },
+        {
+            "name": "demo.mail.host",
+            "type": "java.lang.String",
+            "description": "SMTP host. No default: absent means the application must not start.",
+            "sourceType": "com.ankurm.configprops.props.MailProperties"
+        },
+        {
+            "name": "demo.mail.port",