Support span#error in toolkit

[IanCao]

Please answer these questions before submitting pull request

• Why submit this pull request?

• Bug fix

• New feature provided

• Improve performance

• Related issues

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Bug fix

• Bug description.

• How to fix?

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New feature or improvement

• Describe the details and related test reports.

[wu-sheng]

@ascrutae Do we need test case for this?

[wu-sheng]

Support #2599

[ascrutae]

@IanCao I suggest that to add error message or an exception in ActiveSpan#error API, Because the user will confused why this span occurs an exception when the span without any error message or an exception.

[wu-sheng]

I suggest that to add error message or an exception in ActiveSpan#error API, Because the user will confused why this span occurs an exception when the span without any error message or an exception.

@ascrutae Exception is a log API, do you suggest to add that?

[coveralls]

Coverage increased (+0.05%) to 16.413% when pulling 292c10b on IanCao:master into ed78dab on apache:master.

[IanCao]

I suggest that to add error message or an exception in ActiveSpan#error API, Because the user will confused why this span occurs an exception when the span without any error message or an exception.

@ascrutae Exception is a log API, do you suggest to add that?

i have added three error methods and test case

   public static void error() {
    }
    public static void error(String key, String errorMsg) {
    }
    public static void error(Throwable throwable) {
    }

plz review~

[wu-sheng]

cc @ascrutae comments inline.

[IanCao]

@wu-sheng please review

[wu-sheng]

inline.

[wu-sheng]

Application toolkit document should update, and add an integration test case for this?

[IanCao]

Application toolkit document should update, and add an integration test case for this?

ok

[IanCao]

Application toolkit document should update, and add an integration test case for this?

doc and integration test case have added

[SkyWalkingRobot]

Here is the test report and validate logs

[wu-sheng]

Document change suggestions inline.