Doing something like this:

SearchMapping mapping = new SearchMapping();
mapping.entity( Item.class )
	.indexed()
	.property( "price", ElementType.FIELD )
		.field()
		.numericField().precisionStep(10); 

results in two @Field instances for price. The reason being is that NumericFieldMapping extends FieldMapping.

This prevents validation of the field configuration. For example each index field should have a single point of configuration.