[java]Fix incompatible types error for number

[bgong-mdsol]

This PR fixes the incompatible types error for numberSchema which has a default value but no format or the format is not double or float.

About issue detail, please see #4612

@wing328 @sebastien-rosset @cbornet @jeff9finger @bbdouglas @sreeshas @jfiala @lukoyanov @karismann @Zomzog @lwlee2608 @bkabrda @jfeltesse-mdsol @jcarres-mdsol @ykitamura-mdsol

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[wing328]

LGTM