Plugin crashes on Eclipse 2018-09 (and Photon?)

[kingjon3377]

On the recently-released Eclipse 2018-09 (i.e. Eclipse 4.9; I seem to recall this also happening on Eclipse Photon when I tried it soon after it was released), the following stack trace appears in the error log, and the Ceylon code in my project is not compiled.

java.lang.NoSuchMethodError: org.eclipse.jdt.internal.core.SearchableEnvironment.<init>(Lorg/eclipse/jdt/internal/core/JavaProject;Lorg/eclipse/jdt/core/WorkingCopyOwner;)V
	at com.redhat.ceylon.eclipse.core.model.ModelLoaderNameEnvironment.<init>(ModelLoaderNameEnvironment.java:65)
	at com.redhat.ceylon.eclipse.core.model.JDTModelLoader$JavaProjectInfos.createSearchableEnvironment$priv$(JDTModelLoader.ceylon:205)
	at com.redhat.ceylon.eclipse.core.model.JDTModelLoader$JavaProjectInfos.createLookupEnvironment(JDTModelLoader.ceylon:211)
	at com.redhat.ceylon.eclipse.core.model.JDTModelLoader$JavaProjectInfos.<init>(JDTModelLoader.ceylon:222)
	at com.redhat.ceylon.eclipse.core.model.JDTModelLoader.<init>(JDTModelLoader.ceylon:267)
	at com.redhat.ceylon.eclipse.core.model.JDTModuleManager.newModelLoader(JDTModuleManager.ceylon:59)
	at com.redhat.ceylon.eclipse.core.model.JDTModuleManager.newModelLoader(JDTModuleManager.ceylon:48)
	at com.redhat.ceylon.ide.common.model.BaseIdeModuleManager.getModelLoader(IdeModuleManager.ceylon:95)
	at com.redhat.ceylon.ide.common.model.BaseIdeModuleManager.createPackage(IdeModuleManager.ceylon:131)
	at com.redhat.ceylon.ide.common.model.BaseIdeModuleManager.initCoreModules(IdeModuleManager.ceylon:125)
	at com.redhat.ceylon.compiler.typechecker.analyzer.ModuleSourceMapper.initCoreModules(ModuleSourceMapper.java:91)
	at com.redhat.ceylon.compiler.typechecker.context.PhasedUnits.<init>(PhasedUnits.java:60)
	at com.redhat.ceylon.compiler.typechecker.TypeChecker.<init>(TypeChecker.java:53)
	at com.redhat.ceylon.compiler.typechecker.TypeCheckerBuilder.getTypeChecker(TypeCheckerBuilder.java:159)
	at com.redhat.ceylon.ide.common.model.CeylonProject$16$1.$call$(CeylonProject.ceylon:822)
	at com.redhat.ceylon.ide.common.model.withCeylonModelCaching_.withCeylonModelCaching(CeylonProjects.ceylon:50)
	at com.redhat.ceylon.ide.common.model.CeylonProject$16.$call$(CeylonProject.ceylon:807)
	at com.redhat.ceylon.ide.common.model.BaseCeylonProject.withSourceModel$canonical$(CeylonProject.ceylon:503)
	at com.redhat.ceylon.ide.common.model.BaseCeylonProject.withSourceModel(CeylonProject.ceylon:495)
	at com.redhat.ceylon.ide.common.model.CeylonProject.parseCeylonModel(CeylonProject.ceylon:804)
	at com.redhat.ceylon.eclipse.core.classpath.CeylonProjectModulesContainer.resolveClasspath(CeylonProjectModulesContainer.java:329)
	at com.redhat.ceylon.eclipse.core.builder.CeylonBuilder.build(CeylonBuilder.java:863)
	at org.eclipse.core.internal.events.BuildManager$2.run(BuildManager.java:798)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:219)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:262)
	at org.eclipse.core.internal.events.BuildManager$1.run(BuildManager.java:315)
	at org.eclipse.core.runtime.SafeRunner.run(SafeRunner.java:45)
	at org.eclipse.core.internal.events.BuildManager.basicBuild(BuildManager.java:318)
	at org.eclipse.core.internal.events.BuildManager.basicBuildLoop(BuildManager.java:370)
	at org.eclipse.core.internal.events.BuildManager.build(BuildManager.java:391)
	at org.eclipse.core.internal.events.AutoBuildJob.doBuild(AutoBuildJob.java:145)
	at org.eclipse.core.internal.events.AutoBuildJob.run(AutoBuildJob.java:235)
	at org.eclipse.core.internal.jobs.Worker.run(Worker.java:63)

Here's the "session data" in the "Event Details" for this in the Error Log:

eclipse.buildId=4.9.0.I20180906-0745
java.version=1.8.0_192
java.vendor=Oracle Corporation
BootLoader constants: OS=macosx, ARCH=x86_64, WS=cocoa, NL=en_US
Framework arguments:  -product org.eclipse.epp.package.java.product -product org.eclipse.epp.package.java.product -keyring /Users/kingjon/.eclipse_keyring
Command-line arguments:  -os macosx -ws cocoa -arch x86_64 -product org.eclipse.epp.package.java.product -data file:/Users/kingjon/eclipse-workspace/ -product org.eclipse.epp.package.java.product -keyring /Users/kingjon/.eclipse_keyring

The plugin version is 1.3.3.v20170818-1632-Final.