IO-665 ensure that passing a null InputStream results in NPE with tests

[ottobackwards]

This pr adds a null check for the InputStream constructor of XmlStreamReader. This makes it so that each contractor of type ( File, URL, URLConnection, InputStream ) throws NPE if passed a NULL for that type.

Tests were added as well for each type.

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This change is 

[garydgregory]

Could other constructors benefit from this check?

[ottobackwards]

The other contructors, already throw the NPE so I didn't change them. We could add the check to ensure that thread is always a message though.

[ottobackwards]

Actually, since they use

this(object.somethingThatReturnsAStream()) we would have to change the initialization pattern from this() to some sort of initialize pattern.

Do you have a preference in that area?

They behave correctly, but there is no message.

[coveralls]

Coverage increased (+0.1%) to 89.739% when pulling 2dcd21b on ottobackwards:IO-665 into 6a78ef8 on apache:master.

[garydgregory]

Actually, since they use

this(object.somethingThatReturnsAStream()) we would have to change the initialization pattern from this() to some sort of initialize pattern.

Do you have a preference in that area?

They behave correctly, but there is no message.

I do not see why you'd need anything more than changing methods like:

    public XmlStreamReader(final URL url) throws IOException {
        this(url.openConnection(), null);
    }

to:

    public XmlStreamReader(final URL url) throws IOException {
        this(Objects.requireNonNull(url, "url").openConnection(), null);
    }

[ottobackwards]

That is because you @garydgregory know java better than I lol. Will do

[ottobackwards]

@garydgregory done

[garydgregory]

That is because you @garydgregory know java better than I lol. Will do

;-)