https://www.graalvm.org/ 
class com.oracle.truffle.api.test.polyglot.LoggingTest$9 implements java.util.function.BiPredicate<com.oracle.truffle.api.test.polyglot.LoggingTest$LoggingContext, com.oracle.truffle.api.TruffleLogger[]>
  minor version: 0
  major version: 59
  flags: flags: (0x0020) ACC_SUPER
  this_class: com.oracle.truffle.api.test.polyglot.LoggingTest$9
  super_class: java.lang.Object
{
  private final java.lang.String[] val$loggerIds;
    descriptor: [Ljava/lang/String;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  private final java.lang.String[] val$loggerNames;
    descriptor: [Ljava/lang/String;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  private final java.lang.String[] val$messages;
    descriptor: [Ljava/lang/String;
    flags: (0x1012) ACC_PRIVATE, ACC_FINAL, ACC_SYNTHETIC

  void <init>(java.lang.String[], java.lang.String[], java.lang.String[]);
    descriptor: ([Ljava/lang/String;[Ljava/lang/String;[Ljava/lang/String;)V
    flags: (0x0000) 
    Code:
      stack=2, locals=4, args_size=4
        start local 0 // com.oracle.truffle.api.test.polyglot.LoggingTest$9 this
         0: .line 1049
            aload 0 /* this */
            aload 1
            putfield com.oracle.truffle.api.test.polyglot.LoggingTest$9.val$loggerIds:[Ljava/lang/String;
            aload 0 /* this */
            aload 2
            putfield com.oracle.truffle.api.test.polyglot.LoggingTest$9.val$loggerNames:[Ljava/lang/String;
            aload 0 /* this */
            aload 3
            putfield com.oracle.truffle.api.test.polyglot.LoggingTest$9.val$messages:[Ljava/lang/String;
            aload 0 /* this */
            invokespecial java.lang.Object.<init>:()V
            return
        end local 0 // com.oracle.truffle.api.test.polyglot.LoggingTest$9 this
      LocalVariableTable:
        Start  End  Slot  Name  Signature
            0    1     0  this  Lcom/oracle/truffle/api/test/polyglot/LoggingTest$9;
    MethodParameters:
                 Name  Flags
      val$loggerIds    final
      val$loggerNames  final
      val$messages     final

  public boolean test(com.oracle.truffle.api.test.polyglot.LoggingTest$LoggingContext, com.oracle.truffle.api.TruffleLogger[]);
    descriptor: (Lcom/oracle/truffle/api/test/polyglot/LoggingTest$LoggingContext;[Lcom/oracle/truffle/api/TruffleLogger;)Z
    flags: (0x0001) ACC_PUBLIC
    Code:
      stack=2, locals=7, args_size=3
        start local 0 // com.oracle.truffle.api.test.polyglot.LoggingTest$9 this
        start local 1 // com.oracle.truffle.api.test.polyglot.LoggingTest$LoggingContext context
        start local 2 // com.oracle.truffle.api.TruffleLogger[] loggers
         0: .line 1053
            iconst_0
            istore 3 /* i */
        start local 3 // int i
         1: goto 10
         2: .line 1054
      StackMap locals: int
      StackMap stack:
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.polyglot.LoggingTest$9.val$loggerIds:[Ljava/lang/String;
            iload 3 /* i */
            aaload
            astore 4 /* loggerId */
        start local 4 // java.lang.String loggerId
         3: .line 1055
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.polyglot.LoggingTest$9.val$loggerNames:[Ljava/lang/String;
            iload 3 /* i */
            aaload
            astore 5 /* loggerName */
        start local 5 // java.lang.String loggerName
         4: .line 1056
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.polyglot.LoggingTest$9.val$messages:[Ljava/lang/String;
            iload 3 /* i */
            aaload
            astore 6 /* message */
        start local 6 // java.lang.String message
         5: .line 1057
            aload 5 /* loggerName */
            ifnonnull 8
         6: .line 1058
            aload 4 /* loggerId */
            invokestatic com.oracle.truffle.api.TruffleLogger.getLogger:(Ljava/lang/String;)Lcom/oracle/truffle/api/TruffleLogger;
            aload 6 /* message */
            invokevirtual com.oracle.truffle.api.TruffleLogger.warning:(Ljava/lang/String;)V
         7: .line 1059
            goto 9
         8: .line 1060
      StackMap locals: java.lang.String java.lang.String java.lang.String
      StackMap stack:
            aload 4 /* loggerId */
            aload 5 /* loggerName */
            invokestatic com.oracle.truffle.api.TruffleLogger.getLogger:(Ljava/lang/String;Ljava/lang/String;)Lcom/oracle/truffle/api/TruffleLogger;
            aload 6 /* message */
            invokevirtual com.oracle.truffle.api.TruffleLogger.warning:(Ljava/lang/String;)V
        end local 6 // java.lang.String message
        end local 5 // java.lang.String loggerName
        end local 4 // java.lang.String loggerId
         9: .line 1053
      StackMap locals:
      StackMap stack:
            iinc 3 /* i */ 1
      StackMap locals:
      StackMap stack:
        10: iload 3 /* i */
            aload 0 /* this */
            getfield com.oracle.truffle.api.test.polyglot.LoggingTest$9.val$loggerIds:[Ljava/lang/String;
            arraylength
            if_icmplt 2
        end local 3 // int i
        11: .line 1063
            iconst_0
            ireturn
        end local 2 // com.oracle.truffle.api.TruffleLogger[] loggers
        end local 1 // com.oracle.truffle.api.test.polyglot.LoggingTest$LoggingContext context
        end local 0 // com.oracle.truffle.api.test.polyglot.LoggingTest$9 this
      LocalVariableTable:
        Start  End  Slot        Name  Signature
            0   12     0        this  Lcom/oracle/truffle/api/test/polyglot/LoggingTest$9;
            0   12     1     context  Lcom/oracle/truffle/api/test/polyglot/LoggingTest$LoggingContext;
            0   12     2     loggers  [Lcom/oracle/truffle/api/TruffleLogger;
            1   11     3           i  I
            3    9     4    loggerId  Ljava/lang/String;
            4    9     5  loggerName  Ljava/lang/String;
            5    9     6     message  Ljava/lang/String;
    RuntimeVisibleAnnotations: 
      com.oracle.truffle.api.CompilerDirectives$TruffleBoundary()
    MethodParameters:
         Name  Flags
      context  final
      loggers  final

  public boolean test(java.lang.Object, java.lang.Object);
    descriptor: (Ljava/lang/Object;Ljava/lang/Object;)Z
    flags: (0x1041) ACC_PUBLIC, ACC_BRIDGE, ACC_SYNTHETIC
    Code:
      stack=3, locals=3, args_size=3
         0: .line 1
            aload 0
            aload 1
            checkcast com.oracle.truffle.api.test.polyglot.LoggingTest$LoggingContext
            aload 2
            checkcast com.oracle.truffle.api.TruffleLogger[]
            invokevirtual com.oracle.truffle.api.test.polyglot.LoggingTest$9.test:(Lcom/oracle/truffle/api/test/polyglot/LoggingTest$LoggingContext;[Lcom/oracle/truffle/api/TruffleLogger;)Z
            ireturn
      LocalVariableTable:
        Start  End  Slot  Name  Signature
}
Signature: Ljava/lang/Object;Ljava/util/function/BiPredicate<Lcom/oracle/truffle/api/test/polyglot/LoggingTest$LoggingContext;[Lcom/oracle/truffle/api/TruffleLogger;>;
SourceFile: "LoggingTest.java"
EnclosingMethod: com.oracle.truffle.api.test.polyglot.LoggingTest.createCustomLogging:([Ljava/lang/String;[Ljava/lang/String;[Ljava/lang/String;)Ljava/util/function/BiPredicate;
NestHost: com.oracle.truffle.api.test.polyglot.LoggingTest
InnerClasses:
  public abstract TruffleBoundary = com.oracle.truffle.api.CompilerDirectives$TruffleBoundary of com.oracle.truffle.api.CompilerDirectives
  com.oracle.truffle.api.test.polyglot.LoggingTest$9
  public final LoggingContext = com.oracle.truffle.api.test.polyglot.LoggingTest$LoggingContext of com.oracle.truffle.api.test.polyglot.LoggingTest