mergeEntries = (firstEntry, secondEntry, internalCaching) => {
	switch (getValueType(secondEntry.base)) {
		case VALUE_TYPE_ATOM:
		case VALUE_TYPE_DELETE:
			// No need to consider firstEntry at all
			// second value override everything
			// = second.base + second.byProperty
			return secondEntry;
		case VALUE_TYPE_UNDEFINED:
			if (!firstEntry.byProperty) {
				// = first.base + second.byProperty
				return {
					base: firstEntry.base,
					byProperty: secondEntry.byProperty,
					byValues: secondEntry.byValues
				};
			} else if (firstEntry.byProperty !== secondEntry.byProperty) {
				throw new Error(
					`${firstEntry.byProperty} and ${secondEntry.byProperty} for a single property is not supported`
				);
			} else {
				// = first.base + (first.byProperty + second.byProperty)
				// need to merge first and second byValues
				const newByValues = new Map(firstEntry.byValues);
				for (const [key, value] of secondEntry.byValues) {
					const firstValue = getFromByValues(firstEntry.byValues, key);
					newByValues.set(
						key,
						mergeSingleValue(firstValue, value, internalCaching)
					);
				}
				return {
					base: firstEntry.base,
					byProperty: firstEntry.byProperty,
					byValues: newByValues
				};
			}
		default: {
			if (!firstEntry.byProperty) {
				// The simple case
				// = (first.base + second.base) + second.byProperty
				return {
					base: mergeSingleValue(
						firstEntry.base,
						secondEntry.base,
						internalCaching
					),
					byProperty: secondEntry.byProperty,
					byValues: secondEntry.byValues
				};
			}
			let newBase;
			const intermediateByValues = new Map(firstEntry.byValues);
			for (const [key, value] of intermediateByValues) {
				intermediateByValues.set(
					key,
					mergeSingleValue(value, secondEntry.base, internalCaching)
				);
			}
			if (
				Array.from(firstEntry.byValues.values()).every(value => {
					const type = getValueType(value);
					return type === VALUE_TYPE_ATOM || type === VALUE_TYPE_DELETE;
				})
			) {
				// = (first.base + second.base) + ((first.byProperty + second.base) + second.byProperty)
				newBase = mergeSingleValue(
					firstEntry.base,
					secondEntry.base,
					internalCaching
				);
			} else {
				// = first.base + ((first.byProperty (+default) + second.base) + second.byProperty)
				newBase = firstEntry.base;
				if (!intermediateByValues.has("default"))
					intermediateByValues.set("default", secondEntry.base);
			}
			if (!secondEntry.byProperty) {
				// = first.base + (first.byProperty + second.base)
				return {
					base: newBase,
					byProperty: firstEntry.byProperty,
					byValues: intermediateByValues
				};
			} else if (firstEntry.byProperty !== secondEntry.byProperty) {
				throw new Error(
					`${firstEntry.byProperty} and ${secondEntry.byProperty} for a single property is not supported`
				);
			}
			const newByValues = new Map(intermediateByValues);
			for (const [key, value] of secondEntry.byValues) {
				const firstValue = getFromByValues(intermediateByValues, key);
				newByValues.set(
					key,
					mergeSingleValue(firstValue, value, internalCaching)
				);
			}
			return {
				base: newBase,
				byProperty: firstEntry.byProperty,
				byValues: newByValues
			};
		}
	}
}
@param {ObjectParsedPropertyEntry} firstEntry a
@param {ObjectParsedPropertyEntry} secondEntry b
@param {boolean} internalCaching should parsing of objects and nested merges be cached
@returns {ObjectParsedPropertyEntry} new entry