NOTE
How an Executable Spring Boot Jar Starts
Executable Boot archive layout, launcher/class-loader concept, nested dependencies, and why exact launcher classes are version-specific.
This is a historical learning note and may contain outdated or incomplete understanding.
A Spring Boot executable archive packages application classes plus dependencies in a layout understood by Boot’s launcher support. The manifest identifies launcher/application entry information, and Boot’s loader infrastructure makes nested library contents visible to the application class path without requiring users to unpack them manually.
This is different from a plain JAR whose dependency JARs are not automatically nested-classpath entries.
Exact archive directories, launcher class names, and class-loader implementation have evolved. When debugging startup/class loading, inspect the archive and loader implementation for the deployed Boot version.