SearchResultsWrapper#getFieldData throws ParamException when a search has no matching records

[zero11-0203]

milvus-sdk-java/src/main/java/io/milvus/response/SearchResultsWrapper.java

Line 41 in 9c3adb7

throw new ParamException("Illegal field name: " + fieldName);

Users would expect getFieldData on a valid filedName to return an empty list even if a search has no matching records.

However, it throws a ParamException with Illegal field name instead, because SearchResultData#fieldsData_ seems to be empty when a search has no matching records.

[yhmo]

The getFieldData() returns a List<?>, if we don't throw an exception, we don't know which type should be returned in the List.

List<?> getFieldData(@nonnull String fieldName, int indexOfTarget)