Github user zentol commented on the issue:
https://github.com/apache/flink/pull/4921
Travis failure:
```
Tests run: 17, Failures: 0, Errors: 6, Skipped: 0, Time elapsed: 0.029 sec
<<< FAILURE! - in org.apache.flink.api.java.utils.RequiredParametersTest
testApplyToWithOptionWithLongAndShortNameAndDefaultValue(org.apache.flink.api.java.utils.RequiredParametersTest)
Time elapsed: 0.012 sec <<< ERROR!
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.put(Collections.java:1457)
at
org.apache.flink.api.java.utils.RequiredParameters.hasNoDefaultValueAndNoValuePassedOnAlternativeName(RequiredParameters.java:147)
at
org.apache.flink.api.java.utils.RequiredParameters.checkAndApplyDefaultValue(RequiredParameters.java:116)
at
org.apache.flink.api.java.utils.RequiredParameters.applyTo(RequiredParameters.java:94)
at
org.apache.flink.api.java.utils.RequiredParametersTest.testApplyToWithOptionWithLongAndShortNameAndDefaultValue(RequiredParametersTest.java:195)
testApplyToWithMultipleTypes(org.apache.flink.api.java.utils.RequiredParametersTest)
Time elapsed: 0.002 sec <<< ERROR!
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.put(Collections.java:1457)
at
org.apache.flink.api.java.utils.RequiredParameters.hasNoDefaultValueAndNoValuePassedOnAlternativeName(RequiredParameters.java:147)
at
org.apache.flink.api.java.utils.RequiredParameters.applyTo(RequiredParameters.java:103)
at
org.apache.flink.api.java.utils.RequiredParametersTest.testApplyToWithMultipleTypes(RequiredParametersTest.java:228)
testApplyToWithOptionMultipleOptionsAndOneDefaultValue(org.apache.flink.api.java.utils.RequiredParametersTest)
Time elapsed: 0.001 sec <<< ERROR!
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.put(Collections.java:1457)
at
org.apache.flink.api.java.utils.RequiredParameters.hasNoDefaultValueAndNoValuePassedOnAlternativeName(RequiredParameters.java:147)
at
org.apache.flink.api.java.utils.RequiredParameters.applyTo(RequiredParameters.java:103)
at
org.apache.flink.api.java.utils.RequiredParametersTest.testApplyToWithOptionMultipleOptionsAndOneDefaultValue(RequiredParametersTest.java:210)
testApplyToWithOptionAndDefaultValue(org.apache.flink.api.java.utils.RequiredParametersTest)
Time elapsed: 0 sec <<< ERROR!
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.put(Collections.java:1457)
at
org.apache.flink.api.java.utils.RequiredParameters.hasNoDefaultValueAndNoValuePassedOnAlternativeName(RequiredParameters.java:147)
at
org.apache.flink.api.java.utils.RequiredParameters.checkAndApplyDefaultValue(RequiredParameters.java:116)
at
org.apache.flink.api.java.utils.RequiredParameters.applyTo(RequiredParameters.java:94)
at
org.apache.flink.api.java.utils.RequiredParametersTest.testApplyToWithOptionAndDefaultValue(RequiredParametersTest.java:182)
testApplyToMovesValuePassedOnShortNameToLongNameIfLongNameIsUndefined(org.apache.flink.api.java.utils.RequiredParametersTest)
Time elapsed: 0.001 sec <<< ERROR!
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.put(Collections.java:1457)
at
org.apache.flink.api.java.utils.RequiredParameters.hasNoDefaultValueAndNoValuePassedOnAlternativeName(RequiredParameters.java:144)
at
org.apache.flink.api.java.utils.RequiredParameters.applyTo(RequiredParameters.java:103)
at
org.apache.flink.api.java.utils.RequiredParametersTest.testApplyToMovesValuePassedOnShortNameToLongNameIfLongNameIsUndefined(RequiredParametersTest.java:127)
testDefaultValueDoesNotOverrideValuePassedOnShortKeyIfLongKeyIsNotPassedButPresent(org.apache.flink.api.java.utils.RequiredParametersTest)
Time elapsed: 0.001 sec <<< ERROR!
java.lang.UnsupportedOperationException: null
at java.util.Collections$UnmodifiableMap.put(Collections.java:1457)
at
org.apache.flink.api.java.utils.RequiredParameters.hasNoDefaultValueAndNoValuePassedOnAlternativeName(RequiredParameters.java:144)
at
org.apache.flink.api.java.utils.RequiredParameters.checkAndApplyDefaultValue(RequiredParameters.java:116)
at
org.apache.flink.api.java.utils.RequiredParameters.applyTo(RequiredParameters.java:94)
at
org.apache.flink.api.java.utils.RequiredParametersTest.testDefaultValueDoesNotOverrideValuePassedOnShortKeyIfLongKeyIsNotPassedButPresent(RequiredParametersTest.java:142)
```
---
