Update from Spring 3.7.2 / m2e 1.6 to Spring 3.7.3 / m2e 1.7 causes POM file errors

Question

I am struggling with an issue that came up after I allowed Spring to update from STS version 3.7.2 with m2e 1.6 to STS version 3.7.3 with m2e 1.7. Immediately after updating, all my POM files are marked with an error 'Referenced file contains errors (http://maven.apache.org/maven-v4_0_0.xsd). For more information, right click on the message in the Problems View and select "Show Details..."'. "Show Details" reports "Details information currently unavailable".

I've spent half a day searching for answers but have come up empty. The error doesn't make sense to me, I am sure the maven-v4_0_0.xsd is fine.

Here is my version info before the update:

JNA Library 3.2.7
m2e - Maven Integration for Eclipse (includes Incubating components)    1.6.2.20150902-0002
m2e - slf4j over logback logging (Optional) 1.6.2.20150902-0002
m2e connector for build-helper-maven-plugin 0.15.0.201207090124
m2e connector for mavenarchiver pom properties  0.17.0.201502101659-signed-20150525172209
m2e-wtp - JAX-RS configurator for WTP (Optional)    1.2.1.20150819-2220
m2e-wtp - JPA configurator for WTP (Optional)   1.2.1.20150819-2224
m2e-wtp - JSF configurator for WTP (Optional)   1.2.1.20150819-2220
m2e-wtp - Maven Integration for WTP 1.2.1.20150819-2220
Maven Integration for AJDT (Optional)   0.14.0.201506231302
Maven SCM Handler for EGit  0.14.0.201401060023
Spring Tool Suite   3.7.2.201511261050-RELEASE-e44
Spring UAA Integration (optional)   3.6.3.201411271002-RELEASE
Subclipse (Required)    1.6.18
Subclipse Integration for Mylyn 3.x (Optional)  3.0.0
Subversion Client Adapter (Required)    1.6.12
Subversion JavaHL Native Library Adapter (Required) 1.6.17
SVNKit Client Adapter (Not required)    1.6.15
SVNKit Library  1.3.5.7406
TypeScript  1.7.0.v20151201-1631

Here is my version info after the update:

JNA Library 3.2.7
m2e - Maven Integration for Eclipse (includes Incubating components)    1.7.0.20160603-1933
m2e - slf4j over logback logging (Optional) 1.7.0.20160603-1933
m2e connector for build-helper-maven-plugin 0.15.0.201207090124
m2e connector for mavenarchiver pom properties  0.17.1.201605251832-signed-20160525150658
m2e-wtp - JAX-RS configurator for WTP (Optional)    1.2.1.20150819-2220
m2e-wtp - JPA configurator for WTP (Optional)   1.2.1.20150819-2224
m2e-wtp - JSF configurator for WTP (Optional)   1.2.1.20150819-2220
m2e-wtp - Maven Integration for WTP 1.2.1.20150819-2220
Maven Integration for AJDT (Optional)   0.14.0.201506231302
Maven SCM Handler for EGit  0.14.0.201401060023
Spring Tool Suite   3.7.3.201602250958-RELEASE-e44
Spring UAA Integration (optional)   3.6.3.201411271002-RELEASE
Subclipse (Required)    1.6.18
Subclipse Integration for Mylyn 3.x (Optional)  3.0.0
Subversion Client Adapter (Required)    1.6.12
Subversion JavaHL Native Library Adapter (Required) 1.6.17
SVNKit Client Adapter (Not required)    1.6.15
SVNKit Library  1.3.5.7406
TypeScript  1.8.0.v20160504-1733

Here is the first three lines of the pom.xml showing how the error is marked:

Anyone have any ideas of what is wrong?