Table 4.1-A. class file format version ranges (by Java SE Platform) of JVMS states that all class file versions from 45.0 to 55.0 (both inclusive) are supported for Java SE 11. and 45.0 to 56.0 for Java SE 12.
This means that, say 45.1, 46.46 or 50.91 are all to be supported implicitly. But RI throws an exception:
Exception in thread "main" java.lang.UnsupportedClassVersionError: B (class file version 53.1) was compiled with an invalid non-zero minor version
at java.base/java.lang.ClassLoader.defineClass1(Native Method)
at java.base/java.lang.ClassLoader.defineClass(ClassLoader.java:1016)
at java.base/java.security.SecureClassLoader.defineClass(SecureClassLoader.java:151)
at java.base/jdk.internal.loader.BuiltinClassLoader.defineClass(BuiltinClassLoader.java:802)
at java.base/jdk.internal.loader.BuiltinClassLoader.findClassOnClassPathOrNull(BuiltinClassLoader.java:700)
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClassOrNull(BuiltinClassLoader.java:623)
at java.base/jdk.internal.loader.BuiltinClassLoader.loadClass(BuiltinClassLoader.java:581)
at java.base/jdk.internal.loader.ClassLoaders$AppClassLoader.loadClass(ClassLoaders.java:178)
at java.base/java.lang.ClassLoader.loadClass(ClassLoader.java:521)
at java.base/java.lang.Class.forName0(Native Method)
at java.base/java.lang.Class.forName(Class.java:334)
at Wrapper.main(Wrapper.java:3)