driver-legacy/src/main/com/mongodb/QueryBuilder.java
public QueryBuilder withinCenter(final double x, final double y, final double radius) {
        addOperand(QueryOperators.WITHIN,
                   new BasicDBObject(QueryOperators.CENTER, asList(asList(x, y), radius)));
        return this;
    }
public QueryBuilder withinCenter(final double x, final double y, final double radius) {
        addOperand(QueryOperators.WITHIN,
                   new BasicDBObject(QueryOperators.CENTER, asList(asList(x, y), radius)));
        return this;
    }
Equivalent of the $within operand, used for geospatial operation

@param x      x coordinate
@param y      y coordinate
@param radius radius
@return {@code this}