https://www.graalvm.org/ 
public class org.graalvm.tools.insight.test.InsightAPI$OnConfig
  minor version: 0
  major version: 59
  flags: flags: (0x0021) ACC_PUBLIC, ACC_SUPER
  this_class: org.graalvm.tools.insight.test.InsightAPI$OnConfig
  super_class: java.lang.Object
{
  public boolean expressions;
    descriptor: Z
    flags: (0x0001) ACC_PUBLIC

  public boolean statements;
    descriptor: Z
    flags: (0x0001) ACC_PUBLIC

  public boolean roots;
    descriptor: Z
    flags: (0x0001) ACC_PUBLIC

  public java.lang.String rootNameFilter;
    descriptor: Ljava/lang/String;
    flags: (0x0001) ACC_PUBLIC

  public java.util.function.Predicate<org.graalvm.tools.insight.test.InsightAPI$SourceInfo> sourceFilter;
    descriptor: Ljava/util/function/Predicate;
    flags: (0x0001) ACC_PUBLIC
    Signature: Ljava/util/function/Predicate<Lorg/graalvm/tools/insight/test/InsightAPI$SourceInfo;>;

  public void <init>();
    descriptor: ()V
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=1, locals=1, args_size=1
        start local 0 // org.graalvm.tools.insight.test.InsightAPI$OnConfig this
         0: .line 196
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // org.graalvm.tools.insight.test.InsightAPI$OnConfig this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lorg/graalvm/tools/insight/test/InsightAPI$OnConfig;
}
SourceFile: "InsightAPI.java"
NestHost: org.graalvm.tools.insight.test.InsightAPI
InnerClasses:
  public OnConfig = org.graalvm.tools.insight.test.InsightAPI$OnConfig of org.graalvm.tools.insight.test.InsightAPI
  public abstract SourceInfo = org.graalvm.tools.insight.test.InsightAPI$SourceInfo of org.graalvm.tools.insight.test.InsightAPI