Jenkins build failures due to running out of memory on creating archives

From !1122 (comment 2850180):

22:14:29 [ERROR] Failed to execute goal org.eclipse.tycho:tycho-p2-director-plugin:4.0.9:archive-products (archive-products) on project org.eclipse.escet.product: Error packing product: Problem creating zip: Execution exception: Java heap space -> [Help 1]

From !1128 (comment 2849744):

13:13:24 [ERROR] Failed to execute goal org.eclipse.tycho:tycho-packaging-plugin:4.0.9:package-plugin (default-package-plugin) on project org.eclipse.escet.cif.parser: Error assembling JAR: Problem creating jar: Execution exception: Java heap space -> [Help 1]

We seem to be getting more of these. Due to the error for the product, I thought maybe the archives grow in size and are kept in memory before being written. But, the CIF parser JAR isn't exactly that large.

I guess the question is: why do we get these Java heap space errors?