There are a few small typos in SnippetEvent.toString():

* There is a missing equals sign in the display of the "causeSnippet"
* There is a missing comma before the display of "value"
* There is a missing comma before the display of "exception"

Demonstration setup:

    $ jshell
    | Welcome to JShell -- Version 23
    | For an introduction type: /help intro
    
    jshell> var jsh = jdk.jshell.JShell.builder().build();
    jsh ==> jdk.jshell.JShell@551bdc27

Demonstration of first problem:
    
    jshell> jsh.eval("*").get(0)
    $10 ==> SnippetEvent(snippet=Snippet:ErroneousKey#9*,previousStatus=NONEXISTENT,status=REJECTED,isSignatureChange=false,causeSnippetnull)

Demonstration of second problem:
    
    jshell> jsh.eval("123").get(0)
    $9 ==> SnippetEvent(snippet=Snippet:VariableKey($2)#8-123,previousStatus=NONEXISTENT,status=VALID,isSignatureChange=true,causeSnippetnullvalue=123)

Demonstration of third problem:

    jshell> jsh.eval("throw new Exception(\"foo2\");").get(0)
    $8 ==> SnippetEvent(snippet=Snippet:StatementKey#7-throw new Exception("foo2");,previousStatus=NONEXISTENT,status=VALID,isSignatureChange=true,causeSnippetnullexception=jdk.jshell.EvalException: foo2)