Reject client authentication where client_id has non-printable ASCII characters

[scottcarter87]

Describe the bug
A request to the token endpoint with a client ID containing non printable ASCII characters such as 0x00 (null), 0x0a (line feed), etc. This results in the AuthenticationProviders passing this value to the repo layer where Postgres (and potentially other data sources) will throw a DataIntegrityViolationException when trying to run a select query that contains a clientId like this.

To Reproduce
Send a post request to the OAuth2 token endpoint with the client ID set to "\0x00" or any other non-printable ASCII character with or without other printable ASCII characters. The request will be passed through to the repo layer and will throw an error.

Expected behavior
Expected behavior is that Spring would reject any clientId containing non-printable ASCII characters as either a bad request or unauthorized without ever attempting to lookup the RegisteredClient in the database.

Sample

    @DataProvider
    private Object[][] invalidClientIds() {
        return new Object[][] {
                // Null in hex
                { "\0x00" },

                // Line feed in hex
                { "\0x0a" },

                // Escape in hex
                { "\0x1b" },

                // Mix of printable and non-printable ASCII characters (escape character + 'a')
                { "\0x1b\0x61" },
        };
    }

    @Test(dataProvider = "invalidClientIds")
    public void postForAccessTokenWithNonPrintableAsciiCharacters(final String clientId) throws Exception {
        getMockMvc().perform(post(OAuth2.TOKEN_ROOT)
                        .contentType(MediaType.APPLICATION_FORM_URLENCODED_VALUE)
                        .param(OAuth2Constants.Parameters.GRANT_TYPE, AuthorizedGrantType.CLIENT_CREDENTIALS.getValue())
                        .param(OAuth2Constants.Parameters.CLIENT_ID, clientId)
                        .param(OAuth2Constants.Parameters.CLIENT_SECRET, ServiceAccount.CLIENT_SECRET))
                .andExpect(status().isUnauthorized());
    }

    @Test(dataProvider = "invalidClientIds")
    public void postForAccessTokenBasicAuthWithNonPrintableAsciiCharacters(final String clientId) throws Exception {
        getMockMvc().perform(post(OAuth2.TOKEN_ROOT)
                        .with(httpBasic(clientId, OAuthClientDetailsTestData.ServiceAccount.CLIENT_SECRET))
                        .contentType(MediaType.APPLICATION_FORM_URLENCODED_VALUE)
                        .param(OAuth2Constants.Parameters.GRANT_TYPE, AuthorizedGrantType.CLIENT_CREDENTIALS.getValue()))
                .andExpect(status().isUnauthorized());
    }