= AspectJ Java version compatibility

For reasons described e.g. in https://github.com/eclipse-aspectj/aspectj/issues/139#issuecomment-1072946123[this comment],
for AspectJ users it has become a little challenging to find out which minimum AspectJ version is required in order to
process byte code or compile source code using features of a certain Java language version. Since Java 10, this cannot
be easily concluded from the AspectJ version number anymore, and we are sorry for that. So here is a little overview:

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|===
|AspectJ version |Java version |Comments
|1.9.21 |21 |AspectJ compiler requires JDK 17+ during build time. During runtime, AspectJ still only requires Java 8+ for both compile-time and load-time weaving. Pure Java code can be compiled down to as old as 1.3 byte code level.
|1.9.20 - 1.9.20.1 |20 |
|1.9.19 |19 |
|1.9.9 - 1.9.9.1 |18 |
|1.9.8 |17 |AspectJ compiler requires JDK 11+ during build time. During runtime, AspectJ still only requires Java 8+ for both compile-time and load-time weaving. Pure Java code can be compiled down to as old as 1.3 byte code level.
|1.9.7 |15, 16 |
|1.9.6 |14 |
|1.9.5 |13 |
|1.9.3 - 1.9.4 |12 |
|1.9.2 |11 |
|1.9.1 |10 |
|1.9.0 |9 |
|1.8.0 - 1.8.14 |8 |
|1.7.0 - 1.7.4 |7 |
|1.6.0 - 1.6.12 |6 |
|1.5.0 - 1.5.4 |5 |
|===

Older versions omitted.

FYI, here is a brief overview of
https://docs.oracle.com/en/java/javase/18/language/java-language-changes.html[Java language changes since Java 9].
They basically correspond to the new Java language features supported by AspectJ versions for the respective Java
versions.